Some of the obstacles to the rent to own options are:
Rent/downpayment are not sufficient to cover the necessary loan qualifications for you ever to refinance into traditional financing. This is no problem if you are entering into a infinite contract with the seller; however, becomes the deal breaker if you have a "due and payable" clause that requires you to refinance out of the contract in one, two or five years. Traditional financing will require you to evidence down payment funds into the home and will only allow any funds over and above "fair market rent" as credit for any down payment.
You run the risk that the owner is not timely paying the taxes and insurance, despite you providing the funds. Of course, he/she runs the same risk if you are required to make the payments and don't. More than one seller or buyer has lost their home to the tax collector for non-payment of taxes. If you go forward with any rent to own option, pay the few dollars for a third party contract collection company to handle all funds and payments.
Keep extremely detailed records and make all payments in check or money order and keep the canceled checks and all bank statements showing the funds coming out of your account. If you cannot document it and prove it on paper...it did not happen (from a lenders perspective).
Remember, your name is not on the title so essentially you will be remodeling someone else's home. Think very carefully...and consult legal counsel.