Ok here is how I made the pipe tunnel. 1/64 plywood flexes very easily so you can wrap it around into a tunnel with very little trouble. We marked the length of the pipe tunnel, and cut the plywood. Then we just wrapped it around nothing, placed it in the fuselage and tack glued it in the front former and a piece of wood we glued on the wing. When the glue was dry, I ran Elmer's white glue where the plywood joins the fuselage sides, let it dry and cut the excess off. And there you go, a pipe tunnel. Grandpa got this idea from Vic Macaluso who passed it on to me.
Today we spent quite a while making up the landing gear platform, where we have a hole for the pipe and then 3/8 clearance from there up. Didn't get to mounting the gear yet since it actually took quite awhile.