Not sure exactly what the question is you're asking, & you do not say what thickness of 2x2" steel tubing you used. Are you talking about relocating your coupler? My original tongue modification used a 2x2" tube of approx 10gauge (more than 1/8" thickness but less than 3/16"). The tube extends approx 16" forward of the original coupler mounting plate which I inverted. I mounted a coupler which looks very similar to yours, on the 2x2" tube so the 'nose' of the coupler is approx 21" forward of the original mounting plate, 10 1/4" between rear of coupler & mounting plate. See pix in this thread -
http://tnttt.com/viewtopic.php?f=35&t=6 ... 1#p1085971 - My TD weighs 980# on the wheels with tongue weight of 160-175#. I've towed it more'n 25K miles since the build over most every kind of road/terrain. The tongue mod & coupler still look exactly the same as when built, no 'deformation', twist, or other problem.