and (assuming I pick the right device) even read in pouring rain or the shower if I wanted to, so tub reading ceases to be a problem.

With the "wrong device", you can get a tablet dry bag and still be good. This is the one I got for my Boox go color 7. A waterproof device is nicer, but if you're not willing to sacrifice whatever else for one, you still have a cheap, reasonably easy option.