If I may suggest a slightly creative way to finance this acquisition --
Since you already own other parks and have a sizeable down payment, either get an institutional lender to place a junior mortgage on one of your parks (if they are already encumbered) and/or have the seller carry a loan secured by one of your existing parks.
That leaves the newly acquired park free and clear. hmmm...
This strategy opens up more capital than a traditionally financed arrangement.
Keep us posted,