When I want to get a "fingerpicking" type of sound I use 2mm Dunlop stubby picks. I find that the more dense a pick is the deeper tone you will get. The 2mm Dunlops are good for this. They have a tapered tip so the string tends to slide off it.. rather than snapping off the end of a straight edge pick.

I think a two sided guitar pick with what you're talking about wouldn't be too bad... You could take a standard "hard" pick and coat the end in a rubber compound... this would give teh player the ability to play regularly... while still having the versatility of the softer material. I think that a rubber compound over a hard pick would work well... Anyway... good luck with that. Send me some when you get it figured out!! haha.