My dad has done this with a number of his rental properties, although they are mortgage free. He charges a higher payment than typical rent for the area, along with a down payment. For the first two years the payments are considered rent. If they stay in the home after two years, the home is put in their name, the rent payments and down payment are applied to the purchase price, and he collects the payments as the mortgage holder, or they can get a traditional mortgage and pay him off. If they leave during the first two years, all money is forfeited. He has in his contract that they can paint, do minor remodeling, etc. You could write up the contract however you want. He has had good success with this. Only one of the homes he does this on (about 7) have actually gone past the two years, so he's been able to make some extra money on rent. You'll always have the chance that she will move out or cause damages, but you'd probably be able to find another renter, or could put it for sale at that point. Maybe the market would be better then. With you having a mortgage, not sure how that would work.
For insurance purposes, most major companies will put the home in her name with you as additional insureds (similar to a mortgage company) as long as there is legal paperwork drawn up showing this is a lease purchase, bond for deed, however it is titled in your state. If not, you would just insure it as a rental property and she would need to get coverage for her belongings. You can always call your insurance company first, just to make sure. If you need rental property coverage on it, you can write that in your contract as an extra expense for her.