I am finally ready to begin bringing all of this together!
Using some old fence rail and my trailer ramps, I have mocked things up so I could get some final dimensions and order the tubing needed to tie my two frames together. The chair wheel has a 4" lead, and I ended up with a 45" track (70% of wheelbase).
My tubing will be ready for pickup in the morning, and I should be back here with a photo after my first actual roll sometime next week, weather permitting!
I never could have even *started* this project without all of the great help I have received from you folks here, and I thank all of you so very much!
He who so shall, so shall he who.