Luke,
For Fuzzy Wuzzy we use a dual axle (Tor-flex) Triad with 8 supports and a Suburban with the 6 l engine, HD transmission, suspension and rear axle. Total max combined weight is 16,000# - just on the fence - towing is no problem hills or not - we get about 9 mpg.
For long distance towing I would go with a diesel truck.
Bengt Johansson