In Michigan, if the wheels and axles are removed from an non-motorized RV or manufactured home, mobile home and in a mobile home park, it's called "manufactured housing" and the property tax is set at $3/month or $36/year. If owned by a Michigan resident and it's their lived in principle residence they can also qualify for a homestead exemption reduction.
If the wheels and axles remain on the unit and registered/titled in Michigan in at a park, at home, or anywhere else it's called an RV (non-motorized only). The one time tax in Michigan when first registering the purchase of it is according to it's axle/total unloaded weight as manufactured in 3 classifications with the highest being a one time max cost of $300 good for a lifetime as long as you own it no matter with no other taxes or registration needed or additional costs. The max of $300 if owned and used for even 15 years is $20/year or $1.67/month.
If motorized it's called a vehicle and has higher yearly vehicle registration taxes but Michigan has NO personal property taxes so overall it's very reasonable also.