All I can say is WOW, that is the most well thought out, best engineered home built I have seen anywhere, I have been considering the tower for my 17' machine and can really see no good reason for using 10"x 12ga wall tubing, it is the wires that hold the tower up, I have seen several AREs and Skystreams on 85' tilt up towers using 4" and 5" tubing, again, you 20' machine is just awesome, if you ever sell plans put me first on the list.