Sheeted a Gremlin? Nope. Just build it to the instructions. I assume the instructions are per Jim Reith's or Eric Henderson's original design.

The only reinforcement recommended was for the bottom center 6" or so to be glassed with lightweight cloth (2 or 4 oz, or 6 if that is all you have) and epoxy, but don't smear it into the foam. This is mostly for landing damage, but you can practically forget the glassing step for a lighter plane.

Eric's original design wings were not even covered -- just bare foam.

I hope I'm not leading you astray. The ARC kit may be different than the RA cores version. If you have two 6" or 8" plywood center spars glued to some pine bearers which take screws to your downspout fuselage, embedded into the top half of a symmetrical foam wing, than it's got the same basic design, and shouldn't need wing sheeting anywhere. Only fiberglass tape is recommended on the wing's thickest part.

The more weight you add to these, the worse they fly (the wider they turn)