I always re-create the financials based on how I would run the Park, not how the Seller has operated it.
You can use their revenue as a starting point, but will need to adjust it depending on your plan for POH's and also subtracting non-collections expected. Some people add a small sum for the one time purchase of vacant POH's, and others not. On top of that I personally don't give anything for empty pads since they don't make any money, and won't without an additional investment.
The same type exercise for expenses - okay I will have a management fee, accounting and marketing, insurance, lawn / snow service, fixing roads, reserve for capital improvements, utilities, and whatever else.
If you haven't already purchased the MHU Due Diligence Manual it comes with a lot of templates that maps these buckets out as a good starting point, and I have tweaked it over time to meet my specific needs. Once I have filled it out I know what the Park is worth at various capitalization rates and use that to craft my offer.