When people refer to this forum as a "gold mine," it is threads like these that are the "gold" in the mine. The essence of this business is summed up in this thread, which is that you have to get comfortable with what the law says and what risks you take when you seek your advice and advisors.
The state association is a great place to start in every state; and just about whatever might end up getting you in proverbial "hot water" will be based on STATE law which is different in every state. You'll be tried in state court and I would say (have said) typically your company ought to be based in that state (the state of the real property). I would use an LLC for flexibility unless you have a reason to do something different. To the best of my knowledge, LLC's are available in all 50 states (it started in Wyoming).
With that in mind, keep in mind also that specific advice in this forum can be very state-specific.
What is and is not allowed with respect to "renting" versus "selling" is, in the end, something that you will have to convince a judge, jury, insurance executive, or someone else (plaintiff's lawyer, regulator) with respect to.
In practice, property law and contract law are both so-called "common law" and are based on state statutes interpreted by precedent and analogy. Was it a "sale?" or was it not a "sale?" and "When did the sale happen" and "what was transferred to whom at what time?"
The difference between a sale with a long-term lease and a rental and a rent-to-own is very subtle when the same parties control both the lease office and the sales office. In the end, the economics of the transaction include some rent and some property rights that are conveyed over time to the buyer, if they finish the "term." What you call what only matters when you're hauled before someone to explain.
My comfort zone extends to have (since 2012) only used a licensed creditor and my wife's MLO license to originate Dodd-Frank compliant mortgages on "real" sales. Since we go to the trouble of trying to do it right, I am counting on the worst thing that could happen is that we are told to stop doing that and start doing it "wrong." They look exactly the same from the customer's point of view, but the transaction costs are higher for the "right" way.