I personally prefer to put the management team together on parks as I’ve not found PMs that dedicate enough time to a park as they are juggling a volume of properties and they are remote just like you are. 10% fee isn’t an issue but when they don’t stay on top of things their communications, reporting and follow through will suffer.
On the ground doesn’t necessarily mean they need to live in the park but they need to be close by and available when something comes up and communicate with tenants.
A good manager who performs well, good systems, operations plan and a good maintenance man are essential to smooth sailing. Any good PM should have these in place to do an excellent job. Weak spots in any of these will cause issues.
Well testing should not be an issue at least not where I am in SC.