here's a tip for removing the gap take some light ply, 1/16 will do, trace the wing root rib out for both sides, after you have done this slide wing tube in wing then apply small amount of vasoline at the connection area mix epoxy with some micro balloons to use as a glue and filler.
slide ply rib on the wing tube after applying epoxy mix.
before you slide wing into fuse take wax paper and protect fuse from epoxy so you dont glue the wing to the fuse.
then slide wing into fuse and allow to dry,holding the wing with some tape so the wing has a nice tight fit you should spin the wing tube so it doesn't become glued also.
as well as being carefull at the wing alignment pins you don't have to glue everything at once the final filling and finishing can be done after the first step and the wing is separate from the fuse.
a fast dry epoxy works best but 30 min. works also,its a little runny so you should use allot of the micro balloons, so the epoxy is like a fluffy paste.
when dry remove wing and fill any extra gap with more micro balloon epoxy mix and sand smooth.
repeat for other side.