Anyone with experience towing with a Suburban

I won't comment on the weight issues as you seem to understand this. You original question was on length. I pulled two TTs with a 3/4T Yukon 8.1L engine. The engine size would relate to your weight question and hills, but I beleive the 3/4 suspension also helped little more than you'll have with length. With all that said, both TTs were ~28BHS models that ran about ~32ft ball-to-bumper. I used an Equilizer hitch on both and set nose slightly down. With nose even/high i had sway issues. Set up properly I was very happy with them. There was a little suck in/out with large semi's passing fast but all in all I had good towing experiences over ~15-20K miles in ~10yrs.

Not to change your mind, but I didn't really know what good towing was until I got a 5er last year...