Unique Rental Opportunity question

[Devin Borders]

Hey everyone! I have a question about a version of seller financing that I'd like to post to the group. My wife and I are looking at buying a townhome in an up and coming area right outside of Charlotte, NC. The current owners want to sell the property and then rent it back for a minimum of two years. I've come to learn that they have about 15-20k in appreciation that they want to take advantage of in order to pay off some credit card debt. They also want to "simplify" by just renting. Here is the scenario I was thinking about, but wasn't sure how it actually works. 

What if we offered them 15-20k in cash up front as kind of a down payment on the house and then took over their mortgage payments. But then they would rent it back from us at a higher rate. I know this sounds a little nuts, but it seems to solve a lot of "problems". It allows us to get into the property much cheaper than the required 15-20% down. It gives them the ability to pay off their debts. And it also allows us to take over the property. 

My question is, is this possible? Is it dumb? What are everyone's thoughts? Any advice would be greatly appreciated.