Maybe take a lesson from the Ohio Turnpike, which I have never used but I did google it.
At RV Parks have a Kiosk that can issue a ticket for overnight use. Set aside X amount of sites just for overnight. Have it set up to where you can only pull in after 5pm and have to leave by 8am, if want to stay earlier or stay later you have to buy a site at the Park. But leave these overnight sites for travelers just going from point A to point B. the amount charged would depend on the amenities. If the overnight sites are full then you either have to buy a regular site or move on.
We have put our $$ in an envelope and dropped it in a slot many times and I see no need for any hookups other than electric. Pull in, test the electric, plug up, and then be ready to pull out the next morning.