[BWE]

Rob,
Just a thought about your fiberglassing problems. There are two ways that I know of to stop the "melting" issue. (which is caused by the way by the Styrene in the resin. Styrene, I've been told, is also the main component of most foams (styrofoam?)
1: Cover the foam with regular white glue, you'll probably need to give it a couple of coats, and make sure all the pinholes in the glue are well filled. Then just fiberglass over the whole thing like you normally would. You may want to touch the hardened glue with a little sandpaper to roughen it up (may help the FG to "stick")
2: Use a Epoxy resin which will not contain Styrene. Many "Marine Grade" resins are Epoxies.

Just as a note of interest, you could use the styrofoam sheets that are used to insulate basements/houses. If you made a solid blank of the entire shape you where trying to build, you could then FG over it and "melt" the foam blank out of the middle with acetone (which will not harm cured fiberglass). I've seen it done when making prototype kayaks. Oh, and the "sludge" that the foam melts into should be sealed into a can (large paint can, etc.) and can be disposed of as hazardous household waste.

Hope this helps!

Cheers,
Dave