We have double towed on occasion at 83 feet. So far through CO, WY, NE, KS, NM & TX. Old school '83 KW with 255" tandem wb, 36' triple axle 5th, and either 16' tandem axle enclosed cargo or flat car hauler (20' w/tongue). I mostly run secondary and local paved roads and avoid Ports of Entry. With the big truck we do look large, but it looks to have the right proportions. If I was towing with a large dually like a 450/550 or so, then it would look odd. I haven't scaled the total, but it's probably around 52,500. I run two brake controllers, and the lighting/brakes on the second trailer are entirely separate from the 5th wheel circuits. Also have 3 cameras on the back of the 5th to hook up and watch the tires and other things. We don't double tow routinely, just on certain dedicated trips.