I have found that the CA is nice to tack the wing in place as the epoxy cures!
At least in the profile ARF's I've had, the wing to fuse fit is never perfect (it isn't perfect in the kits I've had either). So I stuff in some soft balsa to fill the gaps. Once done then the CA does a nice job holding the wing tight. Then I'll lay in a bead of 30-45 minute epoxy to seal it up. That's almost necessary for a glow powered model. Of course I know you won't have to worry about that
, but it still adds a nice supporting filet to this important joint. I do hit the joint with a little heat from my heat gun to flow the epoxy into a nice smooth line--this evens out the epoxy along the entire joint, and also lets it flow into any small remaining gaps between the wing and fuse.
FWIW, I like to leave the black magic marker line on the plastic covering--the one I use to mark where to remove the plastic film on the center section of the wing. When it gets covered by the transparent epoxy bead, it actually looks cool--like a black pin stripe. Also it makes the typical brownish color less objectionable in my opinion.