From someone who is used to similar situations, the main tip I can offer is to avoid remaining passive. Move often, shake yourself, scream even. Sitting down and focusing will make you asleep, unless you're really passionate about what you're doing.

From what I've heard (and it agrees with my anecdotal experience):

One of the things that takes the most strain when you skip sleep is your heart. Sleep is one of the times when your heart muscles get to rest a bit more, so it can struggle to pump blood when you don't rest

Along those lines, drinking plenty of water and staying hydrated can help make your blood consistency a little thinner and easier to pump.

I'd also consider trying to eat foods that aren't too high in fat, and don't have too high of a glycemic index. Lots of fat all at once can make you feel heavy and tired, exacerbating tiredness, and foods high in glycemic index that contain more simple sugars and less fiber will spike your blood sugar, resulting in a crash that I would also expect to exacerbate tiredness.

The last thing I'd add is to keep in mind that people are extremely bad at assessing how much their sleep deprivation is affecting them. Studies have shown that people are genuinely dogshit at it, and will consistently think they're performing about average while producing horrible results in cognitive tests. Remember that even if you feel like you're doing fine in terms of ability to think, objectively you aren't and are operating at a significantly diminished capacity, and you just can't tell.

Tldr, stay hydrated, eat foods without a ton of fat and that are lower glycemic index, and remember that your brain is really dumb when you don't sleep, even though it often won't feel like it

Set a timer for hydration. You will forget towards the end of it. All the things your body does automatically will become less effective. Like obviously your fuse will be shorter. But you'll feel more hungry with less warning, for instance. Satisfying that in a way that might normally make you a bit tired could be enough to make you crash out. But you need to keep eating or you'll feel like starved hell. Keep it light/snackish. Also try to avoid extra stimulation. If you need stimulation to stay awake keep it minimal as you can.

Additionally, recognize the point of damage. If you're finding yourself taking completely unintentional 'microsleeps' (passing out for 15-120 seconds) that's your brain screaming for mercy and you should take rest if it's even remotely possible, and results get truly unpredictable past that point in regards to emotional/mental stability.

Hope that helps, here to answer if you want clarification on anything there

I used to work night shifts and sometimes had to function afterwards, sometimes for long periods of time. What helped me to stay awake and somewhat clear-minded is light physical activity. Don't sit too much, move, walk around, do some squats, do push ups if you can. Get some fresh air. Cold water on the face helps. If your eyes tend to get tired get some eye drops (artificial tears). And of course coffee helps too.

Also be careful, it's easy to lose balance in a sleep deprived state. So no dangerous surroundings if you can help it.

I used to have to pull an all nighter 1-2 times per week for a terrible job I had. Typically 26-30 hours, so not quite the big one you're looking at.

If you're in a car for part of it, or otherwise idle, take some naps! A few 20 min naps will completely revitalize you for some time. Apart from that, light physical and mental stimulation goes a long way

Regarding the nap thing: if you have the time, taking a strict 20 minute nap will help you get a bit of energy without feeling too groggy afterwards. You want enough time to just barely fall asleep and then get kicked awake before you fully passout.

Creatine is very helpful for reducing the effects of sleep deprivation. I'm not sure what dose would be ideal, but I would expect it to be pretty large, like 20 grams.

Drink a lot of water and eat enough food. I need roughly an extra meal’s worth of food if I stay up all night. Don’t eat it all at once though, because that can make you sleepy. Listen to pumpy music if you can, and if it becomes possible to nap, up to 45 minutes helps me, but between that and about 4 hours, it just gets worse.

I was going to say that unfortunately strong (often illegal or prescription only) stimulants are the only real answer to this, but as you mentioned, you've already tried your ADHD meds, which are either amphetamine or methylphenidate.

So there are only obvious things left, like cold showers and caffeine (400mg max/day), which can also be dangerous, because your heart is already stressed. I think naps (up to 3 hours) will only make things worse, because you are unlikely to be in REM and deep sleep for a significant time and heart strain will spike after waking up again.

Be careful and check your pulse and blood pressure, if you can. Pressing two fingers right below your wrist for pulse and feeling your heartbeat pounding in your neck indicates dangerous blood pressure if you can't accurately measure these.

And most importantly: As soon as you get dizzy, have chest pain, or in the worst case, feel tingling or numbness in your left arm and/or neck, you MUST stop, lay down in the recovery position and have someone check up on you or call an ambulance, as these symptoms can be early signs of a heart attack.

Budget time for sleep. Period. It might take a bit of strength to commit to that based on whatever situation you are in, but it just takes practice.

I have been in situations where I was absolutely forced to be awake for about 5'ish days but nothing else in my life after that ever forced that requirement. All-nighters were always a decision I made willingly and they never really worked out well for productivity.

Still, I am a shitty sleeper and at this very moment, I only have time to finish this comment and get about 4 hours sleep in a strange hotel before I need to wake up for work. However, I am older now and less sleep seems to be the norm for my body.

Managing being exhausted is a personal thing. Aside from drinking more water or coffee, I don't think there are going to be many suggestions that will really help more than that.

Don't drink bottomless coffee. At a certain point it just makes you conk out

Power naps? In the car (since you're not driving) or at any point you can get even 5-10 mins. Get a sleep mask and ear plugs if you need to. Try to sleep max 15 mins at a time, so you don't get that super groggy feeling. Set an alarm or timer. If you drink coffee or tea, supposedly if you drink it just before your nap it will metabolise while you nap and give you a boost when you wake up.

Go for a walks in between to energize yourself. You can also do a sort of walking meditation to try and reduce stress, just kind of look around at the colours, light, shade and movement, listen to the sounds around you (and the gaps between sounds), the feeling of your feet meeting the ground and lifting up again, etc. Try to just take it in as pure perception and if you start thinking, just return to the physical sensation you are focusing on. Even 10 mins will do.

Eat an apple or two for a healthier sugar rush.

When I need to get through my own ADHD episodes when I'm struggling like this so I generally move to things like reading or writing or drawing. The idea that is to keep my brain moving on some sort of thought so that it can't fall asleep.

If you're focused on something you can't sleep at least in my experience ( I focused on things hard enough to end up keeping me awake when I was supposed to sleep )

Best of luck comrade. You got this