To make adjustments, I wrap sand paper onto an old wing tube, sand the fuselage sides where necessary to achieve alighment, then use balsa wedges to shim the tube in position. Once everything is good, I tack the tube in place with thick CA. For final gluing, I use epoxy and lite filler to fill the gaps, messy work but the goal here is to get epoxy into the joint. I used about a roll of paper towels cleaning up the excess.