I do something similar... I use West systems and micro ballons(cures much harder). When the wing and fuse is finished(painted or covered) I bare the wing saddle, wax the wing area with parting wax, mix up epoxy/balloons to a thick consistency and apply a liberal amount to saddle. I wax the bolts and attach wing and perform final incidence checks. Let dry 24 hours and then pop off wing. Start at a corner and work it loose and the whole wing will then pop off. You will be left with a perfect copy of the wing on your saddle including any covering/finishing imperfections! You can clean up the excess drooling down the fuse while wet with paper towls damp with de-natured alcohol. On a painted fuse you can do this prior to fuse being painted and then mask the saddle prior to painting.