My understanding is that flat towing behind a travel trailer is hard on the front end of the vehicle. The reasoning is that as the trailer follows the turn the rear end swings in the opposite direction. The vehicle being towed 4 down is pulled in two different directions. The front wheels scrub pretty hard. This doesn't affect trailers as the second towed vehicle because their only point of contact is the middle axles.
As far as can it be done sure. I've seen plenty of CJs and TJs flat towed behind fivers and tts. If it were my Jeep I'd tow it on a trailer to save the front end and not have to add brakes.