Hey @Kyle Bethune, I second what @Jeffrey H. said. When you buy a community with a high level of park owned homes, you suddenly find yourself in the apartment business, which is quite different from the MH business.
One other thing to consider is the length of time the tenants have been at the property. At the asking price of $365,000, you're looking at a 9.5% cap rate, which is insanely low for such a small park. Some sellers just try to fill up their properties at any cost (usually with unqualified tenants), right before a sale in order to "increase the value" of the property.
Regarding the septic systems, they shouldn't scare you away but always have them inspected thoroughly and try to run an analysis on what it might cost to tie in to the public systems if there is a zoning change or something goes wrong (e.g. usually greater than $100,000).
Here are some last thoughts for you:
Negotiate the price. You make money when you buy the property, so don't over pay for it. Only count income from existing units and consider what the income is if you sell the units and only rent the land (usually less) and apply the cap rate to that. Apply a really high cap rate of at least 15 - 25% so you don't lose your shirt. Ask brokers nearby for input.