Sorry for your loss. Prototyping and testing, is a tough business.
I have built a few Airex sandwich wings, after learning from a very good Slovakian guy. He stressed two things; sanding and priming. Never be happy with the peel ply surface alone, but sand it. Prime the edges of the shear webs, and the contact area of the wing skin, preferably with a low viscosity epoxy. Small gaps, and a good fit, is mandatory, but the primed surfaces will shake hands with your glue bead, even if it barely touches.
I hope you find the inspiration to go on. The aircraft looked so good in the air!
Lars