As a property manager that networks with thousands of others around the country, I don't think it's a viable business model because the cost to build/maintain it outweighs the benefit gained, for you and the Landlord.By the way, the program @Brian LeBow uses is an insurance program, paid for by the Landlord.

What are the benefits to you as a landlord to accept rent in advance such that it outweighs all the negatives cited?

While we enjoyed the positive cash flow, the amount of time we spent on this one property far outweighed the other long-term rentals we owned. 

Valuable resources such as education and connections that the cost of membership, which is $150 annually, far out weigh.

I understand there is park fees to be in a park but do the pros out weigh the cons.

The price for that advice and heeding that advice will far outweigh the cost of raising capital in a manner that is not in compliance with the law.

If you want to go with a hard money loan, there is the potential to get a non recourse loan, but it is going to cost much more than a bank loan, and the cost is likely to outweigh any benefits.Making a loan non-recourse in your situation would remove much of the benefit that the banks would get of bringing your father on as a credit partner.

Yes you will pay maybe 5% extra to use your funds, but in the end won't building the LLC's credit and having future opportunities to leverage that $100k you started with out weigh that interest payment?

That lost chance, the cost of that lost opportunity, that likely far outweighs any cash return you can get investing the same funds elsewhere.As to the doodad... life isn't about dollars and cents... life is a series of experiences, about memories, about enjoying a lifestyle you find enjoyable.

Does the amount of time, effort, and expense outweigh of storing his stuff outweigh the risk that the guy will sue me for not storing his junk for him?