I had planned on doing one of the various mods to store the sewer slinky on/in/behind the rear bumper. But I was recently in Lowes and saw a Hefty brand plastic storage bin that was a perfect fit. It holds two sections of Rhino hose, the angled end that connects to the dump station and the clear tube which let's you enjoy the view while washing out the BW tank.
It fits nicely in the lower left side compartment behind the generator, leaving room for the BW tank wash hose. The plastic bin keeps the storage compartment clean and the bin is easily rinsed out.
Not a fancy mod such as the bumper mount, but it sure was easy.