Google either Family Motor Coach or Motorhome magazine and each year they will list those vehicles that can be towed 4 wheels down. The list of can is much shorter than the list of can't in this case. You can also search by year of vehicle.
However, before purchasing a new TOAD do check the owners manual for proper applications, do not trust a sales persons word as they usually have no real idea.
2013 Ford F350 FX4 4x4 PSD
2013 Wildcat 353LS
2015 Day/Nights Camped 5
2014 Day/Nights Camped 29