I bought a 1 in. dia tube from Graph Tech and cut it to 32 in. long. This allows it to but to spar. No wing sheeting needs removed. The spar is not what fails, its the short unsupported wing tube. The short sleeve pieces are from my first failed wing. Don't worry about the sheer webs. I did a lot of research and found the forces on webbing is diagonal so grain direction is optional. My plane has done many snap rolls and aerobatic flying without problems after modifications. Even though I had to buy 2 airplanes and a $50 wing tube it was worth it. I did a very accurate set up and trimmed by the Triangulation Method resulting in an excellent flying airplane.
Ray