Septic: My due diligence requirements now are no more than TWO homes per septic tank, ideally one. Most septic tanks aren’t large enough to accomodate more than two and the finger systems are inadequate.
Tip: Call or check the septic cleanout companies in the area to see how many times they have been out to the park for service.
Water: Well water is OK, especially if there is a backup or secondary well drilled on the property. If you have only one well and it goes dry, then you may have some serious isssues to deal with. Also, go to the local health department and check on the history of the water readings. In most areas it is a requirement to send in well samples for testing of minerals and contaminants.
Good luck on the park and let us know how it goes.