What I have done in the past is to glue 1/8" light ply to 2 ribs and the spar. In the "plate" I have a blind nut and I use a ring terminal from the cabane to attach it. If you are using streamline (teardrop ) aluminum tubing, JB Weld (original formula ) works exceptionaly well. I normally use a 4-40 cap head screw about 3/8" - 1/2" long to secure everything in place.