Cargo Trailer Conversion - Propane Issue

As ktmrfs says, all of these "laws" that I'm seeing here refer to the legal definition of an "RV". But none of them state that a person can't make their own (as long as they don't try to register it as an RV), nor use one of their own making. A tent doesn't meet any of those "RV" standards, yet campgrounds let tenters in all the time...not sure that a cargo trailer with "camping gear" would be much different. Yes, I know, tents don't have "installed" gear, but where exactly is the line? A large tent can very well have a stove, heater, lights, etc all hooked up to a single propane tank, as well as having a camp sink hooked up to a water supply (campground or otherwise). And what about a cargo trailer with all of the same camping gear, but the trailer itself is simply used as a "hard sided tent"? Again, where is the line?:h Can anyone quote/link an actual law restricting campsites to "certified" vehicles only? Not saying they don't exist, but...a "rule" in a private campground is not the same thing as a "law".