You can put up to about 32 RV spots per acre, but it would be extremely cramped. 20 per acre, you can maneuver and park. They rent from $400 to $450 per month per spot without electricity provided. They make individual secondary meters to put at each spot for electric. I'm working on $10k cost per spot, land, utilities, concrete, and paving. Maybe include a picnic table at each location. That is a possible cashflow of $8k/acre/month. Even at 60% occupancy, you are still grossing $4800/acre/month, more than enough to cover the payment, and still make a profit. 3-4 acres is what I look for, big enough to be profitable, but not too big to saturate the market.
There is a board https://www.workamper.com, where you can advertise for a custodian. I have a friend whose parents didn't quite have enough retirement put back, but they sold their house, bought a travel trailer, and worked at a RV park in Rockport. They checked people in, the wife worked in the little convenient store, he did small repairs, and made sure the lawn service kept the grass cut. They both worked about 10-12 hours per week, got a free spot, free electricity, water, and internet.
The problem with mobile home parks, is the demographic. A lot of folks with disabilities and paycheck to paycheck living live there. You have to deal with squatters rights, and the mobile homes have to be secured in the flood plain according to FEMA rules. They are not mobile and will get flooded in a record turd floater. I wouldn't trust the owners to keep insurance, and since they are semi-permanent you would have to carry flood insurance on them. i have an uncle that lives on my paternal grandparents old place, it is in the 500 year flood plain. FEMA is requiring him to carry flood insurance on his old double wide, as it is underpinned, and the axles and tires have been removed.
CHIEF