Let me get this straight. You want to pay cash upfront for a renting a house that is for sale now rather than purchase it and would a seller consider this? I guess the right answer at the moment is "it depends".
I am not sure what you ar etrying to accomplish, if you buy it cash, can you rent it? You may unless there is an HOA that doesnt allow it. If you are looking tio rent it before you buy it, that is a great question for the listing agent.