The RV's wheelbase is a about 17'6", and the drop in my driveway is about 12-14 inches over that length. I was hoping to be able to run the fridge and extend the slides while parked in the driveway to prepare the RV prior to a trip. I do not intend to keep it there for more than a day, and would NOT live in it while parked in the driveway (my development restricts this behavior). How level does the unit need to be to run the refrigerator and extend the slides safely? Would raising it 6" be enough to run the frig? How level does the RV need to be to extend the slides?