Yep - the last couple posts are onto something. The trendy aspect of it is sure to die off unless some cities change zoning requirements. I actually have been doing a bunch of research on these lately. My family and I end up going to the same place often and rather than haul the 5th wheel I was looking at buying a tiny house aka a park model trailer and setting it up at an RV park near our destination.
At around 50K delivered the cost is reasonable but my big fear is what to do with the thing when I'm done with it.
As for the differences between 5th wheels and park models, a park model is more of a house - thicker walls for more insulation, residential appliances. By definition they must be less than 400 sqft but many have a "storage loft" upstairs that isn't counted in the sqft but is very usable as a flop room for kids.
I still may do this at some point but need to get a better idea of how to resell it. The alternative would be to get an even bigger (eeeeesh - scary) 5th wheel and set it up and leave it. At least that could be sold and hauled away.