My waste dump stuff goes into a plastic bin that fits into one of the street-side storage compartments. A bumper would handle only one hose, I would likely be assembling components each time I dumped if I stored my hose in a bumper. Dishpan-size tub holds 20-foot hose with elbow one end and connector the other, second 20-foot hose for extension, collection of rubber donuts, package of rubber gloves, etc. My fresh-water connection stuff gets a separate tub.
I camp with folks who use a bumper for hose storage, they end up assembling their hose each time they want to use it.
Compartment I use is the one just forward of the rear wheel well, you probably have one near this location, under the dinette.
