At home we have a CalSpas 3 person spa. It weighs about 550 pounds empty, and holds about 225 gallons of water (1876 pounds). Fully loaded, it just barely exceeds the limits of the cargo area in my toy hauler. It's 5'6" by 7', so it would fit perfectly. I'm just speaking theoretically, but you'd have to really love hot tubs to want to bring one with you. Never mind the 220v 30A GFI power requirement, as well as the 30+ minute fill time and the 5 hour heat time, then the dumping of the water.
TV: 2013 Ram 2500 4x4 mega cab w/6.7l Cummins
Trailer: 2013 Palomino Puma 27SBU