Donald, MHP development is incredibly rare.

It's reassuring to hear it's not a rare nightmare scenario I'm in.

In my experience, 40-year terms have rarely made sense.

In my opinion that is rarely necessary for a rental rehab unless perhaps this will be a really nice rental in an upscale area.

My Class A (Indy suburb, great schools) has appreciated and rarely any problems.

How we purchased our property: Combination of Savings, Personal Loan with interest from a family member (4% interest) and a cash loan from Wells at about 8%.

I found this quote that you posted:  "Also proud to say our quads and duplexes (which are rarely offered by other builders) have not only exceeded our estimates for rent & rent growth but value growth as well."

That means their pricing tool is designed to price beneath the rest of the market, which drags the entire market down, especially when combined with their algorithm changes a couple years ago that made pricing (IE lower prices) the #1 factor in ranking.Even if you use an external pricing tool, it gets dragged down by the people using Airbnb's pricing. 

Selling it for $500K and combining that with your $100K could give you more options, like buying a single-family rental or a lake property that generates better cash flow.

When you analyze the deal, it is rarely profitable.