I'm also starting a similar search, and am debating repairing or replacing my current towed vehicle.
My 2000 6 cylinder 4x4 Jeep Grand Cherokee has a failing transmission ($2,700), leaking rear end seal ($500) leaking valve gasket ($150). It has 140,000 miles, and has been towed an additional 10,000 miles, but is in generally good shape, and is set-up for towing.
Most of the vehicles that I am interested in have manual transmissions (my wife's hip replacement would not like that). I'd like another 4x4/AWD SUV/crossover type vehicle, with good mileage.
Here's the 2014 FMCA Dinghy Towing Guide:
2014 Dinghy Towing GuideThe 2013 towing guide actually was more comprehensive, and had better information.