I still use the same method I was shown about 25 yrs ago. Using an incidence meter (assuming a dowel in the front of the wing) hard-shim the back of the wing until the wing incidence is per plan. Then, remove the wing from the fuse, roughen up the saddle with some sandpaper. tape wax paper on the wing where the saddle will sit, apply a bead of silicone seal on the roughened surface, re-install the wing with rubber bands or wing bolts to hold the wing tight against the hard shim allowing the excess silicone to squeeze out the sides. After the silicone sealant has dried you can very easily trim away the excess on either side of the wing saddles leaving you with a fuelproof, fuel- tight, and soft mount for the wing. I also apply where the wing's leading and trailing edge mate with the fuselage to that the whole thing is fuel-tight. Make sure you get the roughened surface of the saddle oil-free before gluing by using alcohol. The stuff comes in several colors including clear, white and beige, so it blends in nice too!