HI Well it has been 20 years ago.... when I did my build o 89 Volvo 610. As I remember..... 35 ft total length .... #3 axel tractor == now wheel base 248 inch ( front axel spinal to middle of the two rear axels) , over hang is ( from center of rear axel hub to the rear of body) 9 ft. The last two feet of the body on the bottoms tapered up, 6 inches . You need to figure balance, with some weight behind the rear axel. Like, location of gen set, water storage, propane storage, house batterie ect. Getting around on the roads with a 26 ft. trailer behind the TC, is no problem. I have several years of high, wide, heavy transport driving in 13 western states. I'm only 12 FT overall Hight, low clearance makes easier to get around. But everyone's needs are different, and every build is a challenge. A lot ot consider , bet worth it. Good luck Roadside