Make sure you check carefully on all the legalities and requirements and limitations for camping on the land. At least here in Vermont there are a fair few specific requirements at the state level, which vary some based on length of time staying, and how many sites are involved, and so forth; and local towns can impose additional requirements via zoning laws, etc. You may find that you legally must have some approved sewer system (not just a vault toilet) for long-term stays, or that camping for more than two weeks is forbidden, or any number of other unfortunate regulations that basically make your idea a non-starter.
As for what I would consider necessary for a rustic RV campsite, I would expect to find a semi-level place for my motorhome, a picnic table, and a fire ring or fireplace. The latter need not be anything fancy; a simple ring of stones in a safe place would suffice. For a seasonal campsite (one that is or could reasonably be occupied for the whole season), water and electricity and sewer hookups are pretty much essential. It sounds like you're more hoping for a seasonal lease on a weekend or short-term stay campsite; I kind of suspect that may be a hard sell for most people, though you really only need to find a few who are interested enough to fill a few sites.
In an RV, a pit or vault toilet is not very useful. It's not suitable for dumping the RV tanks, and the value in having it available to use instead of the indoor plumbing in the RV is marginal at best, particularly compared with the expense of building and maintaining one that the government likes.
My gut feeling is that the scheme is not practical. I really would like to be wrong, but....
