I have been flying my Radian for a year and use nothing to hold the wings.

If the wings are so loose at the root that you are concerned you can pour hot water on the root of the wing. this will swell the foam and tighten up the fit.

or you can do as gopherhunter does and put a layer of tape on the wing, and a layer on the fuse and tape to the tape. I do this on my wood planes so I don't pull the monokote off.  Works great.