I am looking for recommendations for best financing options.The owner is considering financing it, but until they agree, I am planning as if they will not do so.The local credit union I use, who is very investor friendly, is unable to lend on properties larger than 4 units right now. 

Starting with an owner-occupied duplex is a smart way to build equity and gain experience.

Can you then decide to list and sell the house two months later...yes.

Sorry ... gotta ask a "dumb" question here (I've never looked much into MHPs) ...Don't the home owners own the mobile homes while the park owner owns the lots and everything else?

Start by formalizing a lease agreement, evaluating potential renovations to maximize rental income, and deciding on a rental strategy (short-term or long-term).

Often, owners beat up PMCs for a low price, but fail to understand the PMC will often cut corners to make sure they are still profitable. 

He wanted it all sold as a single package with no owner financing.  

I have my second flip under contract and I decided to give Capital 360 a chance to finance this one. 

However, you have to be extremely careful financing 100% of the transaction as you still need reserves, closing costs, etc. and make sure it cash flows.You didn't mention if this would be a rental or owner occupied. 

I would look for investments with owner financing to skip past that requirement.Maybe you can partner with your parents on the first property?