Right-o, Mr Ebb - sorry for the shorthand, should've explained: "EPS" stands for "Extruded PolyStyrene". Can be used with epoxy resin, but not polyester, generally; polyester resin has as a component styrene, which will dissolve EPS foam (you can use polyester resin with EPS foam and get minimal melting damage to the foam, if you kick the resin hard and fast, but... it's dicey. Better not to.).

I am simply going to kerf the foam sheets to get them to conform to the hull curves. Most of the sections are short, so there is not a lot of conforming to be done. Can always fill in any big kerf holes with epoxy and microballoons also.

I tried a buncha glues out. Lots of them will dissolve the foam. Styrene? Dunno, but something in there doesn't like it. On the advice of a 'long time flooring professional' guy who was working at one of the BigBox hardware stores, I tried some really tough floor glue prior to GG. Turns out that on these materials it only bonds here and there... Strong, remains adhesive, but just won't be consistent with grabbing the foam or the ply. Have two 4'x8' sheets of that made up already... Going to try to stick GG in there and see if it will hold well enough that I don't have to waste the material. If so, will use that for less structural stuff.

A guy on another sailing board I read swears by Glidden Porch and Floor for a cheap hard boat paint. Seems like it is a 1-part epoxy. At $25/gal, it's darned affordable, so I am going to get a small bit and check it out. Might be great for a finish on the interior. I have read of others who use garage floor paint also. Likely, any 1-part epoxy paint will do well for this application.