Does anybody else do this? ARF building thing...
Here's something that I saw in a manual someplace, (I forget)...
Before epoxying the wing, use masking tape and run it around the wing cord right at the edge where the wing joins. DO this for both halves. Now epoxy the wing halves together and take care to clean them like you normally would. The tape will at least keep any excess epoxy from sticking to the wing. If some sneaks out, just use a knife to trim it off, then peel the tape off for a nice finish.