Help needed for installing/securing wing tubes
Sounds like an interesting project. I think I would use one long tube that passes through the center section. To attach the outer wings to the tube you could use a #6 bolt that screws into the tube and is supported by a hardpoint. Depending on the thickness of the wing a 1-1/4 or 1-1/2" aluminum tube should be adequate with maybe a .035 or .049 wall. You would need to mount phenolic tubes in the center and outer wing sections to accept the aluminum wing tube. Also would use a dowel for and aft of the tube as an antirotation device. Another way to secure the tube would be to install 2 threaded blocks of wood mounted in the root of the outer wing panels. You could then use a #10 bolt to attach the outer wings to the center section. You would have to make access panels to get at the bolts.