private land camping questions, cell booster suggestions

Seems to me, all the land owner would have to do is not charge for RV parking.
Of course, donations are encouraged, say $25 or $30, to "help defray expenses".
Sorta like the RV dump station at the City Park in Cut Bank, MT. Dumping is no charge, but the last time I used it a $3 donation was encouraged (I dropped $5 in the "Donation Box").
I do not believe any state agency can prevent a land owner from providing a free service.