Scott,
If you remove the rear gas strut, and prop the door up with a dead man or stick, after removing the screws you can pull the panel out past the opening just enough to see inside behind it. If you can locate which hoses are restricting you, make labels and take a picture with your phone. I believe your valves are "Valterra" 3" for waste and 1 1/2" for gray water. Use lots of vasoline to hold the new seals to the valve while installing them. Hope this helps, Fred