My kitchen sink was draining slowly. While taking some dimensions on the rear suspension, I noticed that the gray water drain line was kinked. In the left rear wheel well, there is a metal bracket where the gray water line turns down to the tank. The bracket was compressed and the line was pinched. I was able to bend the bracket back out with needle nose pliers, but I had to make a PVC sleeve to keep the kink out of the line. Thought I would put this out there as something you may want to check on your rig.
Kink in gray water line after bracket has been bent out.
1 inch PVC fitting, cut in half.
Fitting held in place with hose clamp.