Using epoxy resin with the carbon fiber layup is a must if you are to add any real strength to the areas of application. PU with the carbon cloth alone will add almost nothing in strength. I have built many giant scale foam core wings and tail feathers in the past, some with PU for skin attachment and all these days with slow cure epoxy and vacuum. I utilize epoxy and vacuum because of it's superior strength overall and lightweight bond lines. I always start by installing my wing tube sockets, servo boxes or rails, spare extenders as pictured below or landing gear rails. I install everything prior to skinning with PU, and I do so using the foam core shucks lined with handy wrap to keep thing from sticking together. Once in the shucks I place plenty of bricks in place to insure that the pressure from the PU won't hydrolic the shucks off the wing cores during the curing process. After cure, the next day I pull everything apart, clean everything up while insuring that all PU that swelled is carefully sanded back to the (OML) outer mold line of the wing cores. I am now ready to apply my skins, Note: Prior to performing the skinning I always cut 4 pieces of 3/4" thick MDF matching the core shucks perimeter, I place one MDF down on top of the bagging, then the shuck. After the application of the resin and skins I then place the other shuck down followed by the MDF, immediately followed by the bagging and debulking process. The purpose of the MDF is to apply even pressure across both sides of the shucks without any edges of foam caving in due to thin cross sections or holes for things like landing gear pockets, servo pockets or open bays, I use the other two MDFs for the other wing. Another reason I like to use the epoxy for skins is If I have layers of glass or carbon fiber to apply, I am already in the resin process for the skins, and there is no better or stronger time then right now while everything is wet for the application of composite reinforcement. Now this is just the way I do things, and I only mention it as food for thought. I do wish you the very best in whatever you decide to do.

P.S. the wing in the picture that my flying buddy is holding has a span of 164"

Bob