While I am not new to REI, I am new to mobile home /parks investing.

To provide a practical example, I acquired a 60,000 SF assemblage that contained an autobody garage, nearly an acre of surface parking and a 4 unit building in Philadelphia.

Clayton county and the south part of Fulton (specifically College Park) have been great for us.

Our rent-by-the room residents appreciate a lockable bedroom door, a private bathroom, sufficient on-site parking, a large refrigerator and a large washer and dryer (in order of most to least important).

You may pay 1.5m and up for a good one, likely more if parking and balconies, but the play is to buy a multi and then wait and in a few years, turn them into condos and sell them separately - that's how you make the money there.

In my devious mind, I thinking like you that I hire a parking attendant, install gates and charge an entrance fee if I bought it. 

Those buying close to the city are either breaking even or taking negative cashflow and banking on appreciation (or buying all cash and parking money, ha).If you do consider Lowell, I'd also recommend you check out the Fitchburg/Leominster area as well.

It's thorough, easy to use and easy to modify so you can include your own special terms such as quiet hours, how trash service will be handled, parking, and anything else that is specific to your property. 

Consider all the things that could go wrong and see if the lease addresses them: unauthorized pets or tenants, early termination, security deposit, lease violations, late rent, eviction, lawn maintenance, parking, etc.5.

Buy something close to parks, nature, trails, or outdoor venues.