Thanks Coby. I will document my little journey and maybe help others down the line. I don't know why it is black. It is a little coarser than other epp planes I have worked with. I don't think it will matter except for maybe the colored tape.
The spar I am referring to would be a ply spar placed vertically in the foam across the mid seam and probably at the CG. I think it will nicely prevent flexing along the center line during flight.
The battery box may be cut all the way through the plane. A poly floor could then be added on the bottom. I will need a top cover and I will try to fabricate something light with ventilation for the batteries.
The main issue now, not a problem, is a table big enough to work on it. I will have to clear an 8' table. That is a good thing.