I use thick CA to tack the wing into the profile fuse, with the wing/fuse jigged to get the wing straight/square.  Tack the wing in 2 or 3 spots on the top side--after CA has FULLY cured, turn the assembly over and tack on the bottom side.

This may not work for you, but I use 1/2 in. wide electrical tape to seal one side of the wing/fuse joint (profile model), with the tape applied as tight into the corner as I can get it.  Take extra pains  to get the tape very snug into the wing/fuse joint.

I then support the model with the fuse horizontal and the wing at about a 45* angle to the vertical.  I want the wing/fuse joint to be the "down in the valley".  The taped joints are towards the floor.

I use 30 min. epoxy and carefully apply the epoxy only to the very bottom of the valley.  I use a spatula with a small rounded tip, about 1/8 in. radius, to get the epoxy only into the valley.

Apply the epoxy very slowly along the joint, allow it to seep into the joint.  If you are patient, the joint will eventually fill up and if you are careful the epoxy will actually make a small fillet without your help.  Just don't put so much epoxy into the valley that it puddles.

I only do one valley at the time--come back in 2 or 3 hours, reposition the fuse and do the other valley.  After the second valley has cured, pull the electrical tape off and inspect the taped valley--most times you will need to apply just a little epoxy into the previously taped valleys to get them completely filled.  Again, use something with a small point to apply the epoxy, (I have used a round toothpick point) and go slow.  Of course you won't need to do the tape operation again.

If you don't put more epoxy than needed, you will find that the epoxy will stop flowing at the trailing edge. With care, you can get the epoxy to flow into the corner at the leading edge of the wing--the "secret" is to use very little epoxy.  If you use too much epoxy, it flows every where that you don't want it.

When I am finished, I will have an even bead of epoxy along the wing/fuse joint, top and bottom.  There will be a small, natural fillet (about 3/32 inch) due to the surface tension of the epoxy when it was "wet".  This process only works if the minimum amount of epoxy is applied--too much epoxy, and you have a mess.

I have used this technique for profiles with doped fuselage and iron-on covering on the wing/stab.  I trim the iron-on covering at the wing/fuse joint so that the covering ends right at the fuse side--ideally, you want no wood showing.  The epoxy fillet seals the edge of the covering.

Hope this helps a little.

Jim

I do something similar, except that I seal the outside wing to fuselage joint with Sigment.  Being careful to leave no holes, else epoxy runs down the outside wing.  I apply epoxy from the inside as described, but heat the joint from the outside(down side) which makes the epoxy runnier and drives out air bubbles.  In preparation I make a bunch of pinholes into the center section of the wing and into the fuselage.