Do you put their name as registered owner and not fully sign title over until the balance is paid off? If you fully sign over title you relinquish your interest and then you just terminated your contract which is no bueno. If I'm reading your post correctly.
I know someone that has many rent to own mh homes. He has them in parks, does a standard purchase agreement, does the as is where is, puts a clause in there stating the home buyer is responsible for all repairs, upkeep and maintenance, yard work, following park standards, etc. It doesn't mention anything about injury on premises, I don't recall it anyway. He rolls the insurance premium into the monthly payment so the purchaser is never uninsured apart from default. He sells a good product that is properly repaired and put back up to move in ready each time. What state are you in that the eviction process is so hard - do you have a tenant friendly system in your state?
I can see the interest of structuring it like an auto company but the mechanics have to be a little different in the documents I would imagine. Are you worried your buyers will flake on you? It's a legit worry but at the same time, if you get good buyers in there, properly screened, employed, etc.... how often are you intending to repossess. Sorry, my brain goes twelve directions with these kinds of questions, hope some one has some insight because that would be amazing if it was a way to structure them.