No back payments due, but there is a HUD loan for $7k from a previous forbearance.

What little trust I had in the seller disappeared during this process.Now, three days after finalizing all that, I get a text from my agent that they have assigned a street address.

My plan is to put 5% down on a 30-year conventional loan and have the rental income help cover part of the mortgage.

You can probably just go ahead and live in that 5th unit, but I believe whenever you go to refinance it with a bank or what not, the 5th unit will make it require a commercial loan and not residential regardless of what the county records show the property to be. 

There are 10% SBA loans to purchase businesses.

So your $300k number might be what the flipper sold the final product for, less what they purchased it for.

I have given away copies as gifts and loaned mine out to lots of people. 

Does anyone know anyone that does 5% for a vacation home loan? 

I started 23 years ago and bought my first property with 3.5% down using an FHA loan.

Long story short I have never put more than 10% down on a loan and I have never use FHA.