I don't know specifically about Southhaven, but there's both good news and bad news.
And it's the same news.
Most mobile home sellers want cash. But many buyers (like yourself) can'd do all cash. Further, while new/newer homes can often be financed, it's quite difficult to get financing on older mobile homes--say, more than 5 or 6 years old.
As a result, a lot more mobile home sellers end up offering owner financing than you'll find with regular stick-built homes. These aren't usually rent-to-own...for a few reasons. First, a lot of mobile home parks don't allow renters. A rent-to-own is considered a rental. On the other hand, if you buy it (with owner financing), then you are the owner.
If a park does allow renters, then you could do a rent-to-own. However, you'd be in a better position--more protected--buying with owner financing. And it's pretty much the same to the owner. In either case, he's not receiving most of the cash up front.
Tip: When talking to sellers, find out how much cash they really need. For example, you might find a home for $30,000, and it might be a good value at that price. While the owner certainly would prefer all cash, he/she might not need all cash. Maybe the person needs $5,000 to move to Florida and stay with a relative. Maybe the person needs $3,000 for a car repair, but plans to move in with friends. That instantly reduces the amount you have to come up with--dropping from $30,000 to perhaps $5,000.
Also, some investors can put together a deal. I've done that myself. The way it works is: The investor buys the home for all cash, often at a substantial discount. Then he sells it to you with seller financing. Example: The home is for sale at $30,000. The investor makes a cash offer of less than $30,000, which is accepted. The investor offers the home to you for $1,000 with monthly payments of $512 for 7 years. (That's 12% interest.) The investor makes the money by having bought the property for less than $30,000.