You could try to find something for a base, but honestly if I were you I'd just sculpt a tail. Painting sculpey/clay/apoxy sculpt is easier than trying to paint rubber (as I've learned..)
If you haven't sculpted before, I recommend sculpey over apoxysculpt/airdry clay simply because you could take your time getting it right (sculpey doesn't harden until you bake/boil it.)