The sewer hose bumper needs some re-engineering. It needs better caps that don't just fall off on the road (likely taking your slinky with it), attached better (anything more than a spare tire can cause the bumper to just tear off), and of a larger diameter to handle the fittings required by most RV parks on a sewer hose.
Probably the best compromise right now is to buy the larger diameter sewage hose tube and mount that on the bumper... then use the old bumper for fishing rods if it isn't completely rusted out inside, and one can get endcaps that won't fly off on the road.