OK, you've got a lot of items to consider and I don't know all the details. Here are some things to think about.
1) Private utilities and small parks are a tough combo, as it costs as much to drill a water well for 12 lots as 100 lots. They also make a park that size fairly difficult to sell or finance. You'll have to make sure that they are all in perfect order and you will be allowed to make necessary repairs when needed.
2) Master metered gas and electric are extremely dangerous to own and you have to do so for years until that potential conversion occurs (if it happens at all -- we get told that stuff by utility companies frequently and it never pans out).
Now on the good side:
1) For California, those are pretty decent numbers -- much higher potential cap rate than the norm.
2) It has good occupancy
3) It's in California
4) Did I mention it's in California
I would follow the Due Diligence Handbook and see where that takes you. Too early to call. Like all parks, it has good and bad elements. But nothing too bad as to kill it day one, and nothing too good to make it impossible to pass up.