In Mo, it's a trailer tag. PP taxes will depend on the market value or a minimum fee probably. I'll be putting a free standing unit on the trailer. As Sharon mentioned, if it has plumbing, kitchen it may valued as a camper. But, if the entire unit goes on and off like a truck camper, it may not be part of the trailer.
But then again, in Mo. campers are another taxed category. So, if you have a 30k Alaskan truck camper, guess what....
When states adopt new laws or taxation gigs, they will look closely at surrounding states and see what they are doing. Much of something new in one state may be an adoption of what another state already has, it's less work for the govt. types to copy than to create!
Mo is really bad about PP taxes, everything used in a business is taxed, clear down the paper clips (office inventory). I had rentals, they taxed the free standing stove and fridge in each unit!
Your Tax Collector