Oh man, that sucks after all that work. I read once where you can paint the styrofoam with a couple of heavy coats of latex house paint and it stops the resin from dissolving the foam, but I've never tried it...

Anyway, a method that I have used is to make the form up of poster board and cover the entire thing with 2" masking tape. Lay up two or three (or more) layers of 'glass and let it cure. Then rip the posterboard and tape out; you're done. It's probably not as smooth as the foam method, but lots faster as it only takes a few minutes to tape the poster board together.