Dispite what they call it Will -- it will probably desolve, if you use polyester, but epoxy will usually work great !!
One building hint you might want to try also -- drill out the bolt holes, oversize, cote a piece of wooden dowel with epoxy and insert in the holes -- then redrill the mount holes -- this gives you a "hard mount", for your bolts, so they don,t crush the foam or oversize with use !!
Looks good, Happy building, Bill H....