The actual operating records from the current owner supported by their income tax returns as filed are necessary .
A ProForma statement does not account for the real life disasters .
As has been said already the adequacy of the sewer is paramount .
As the new owner all of the electric will need to be up to code and signed off by the local electrical code inspector .
Owners will often do their own electric and plumbing . Some are skilled and some are not .
It is too easy to dig a shallow trench and install PVC or Romex .
In either event it is imperative that the park be up to code for electric , plumbing , and sewage before you spend your money .
PostScript much later .
I should have said that my folks owned a mobile home park with about 10 RV spots . They were along i-5 , visible from the freeway . The RV spots ultimately became full timers . I was an electrician early in life and helped my Pop out with handyman chores and a lot of grounds maintenance . Free gratis , it was good to work with my Pop.
He made very little money after expenses operating the Park but the land value doubled .