I don't really understand why you'd need a community? What is it that people discuss about proxies specifically that couldn't be in a main forum? I'd suggest just posting threads about what you want to talk about and see how they go down.

I use proxies pretty liberally. I even make custom cards for my kids. Since the Pinkertons episode, I haven't bought a new mtg card, but I'm always looking to replace my proxies with used cards and support my LGS in the search for them.