I installed a 35' retractable cord reel in the DEF tank bay, near the rear duals. I ran the cord, powering the reel, over to the engine block heater outlet. My block heater has a switch inside the coach to turn that outlet on and off. Since the bay door is open at the bottom, I just pull the cord out and then close the door. There is enough length to reach the patio area.
You don't have a DEF tank, but many mount the cord reel inside a bay to the frame/wall. The cord reels typically swivel on a bracket, so you can fold it against the wall when not in use.