Hack #25 Rear bumper Caps.

Many people find the rear bumper to be a good place to store the sewer hose(s). They fit rather nicely. You just have to turn them so the tabs on the couplings point to the corners and then wiggle it in/out.
Do keep in mind that you need to keep the inside as clean and dry as you can to prevent rust problems. I treat it in the spring. I run a large rag through several times then simply spray the inside, as best as I can, with black spray paint. Be sure to have some kind of drop cloth under both opened ends as some paint may drip out onto your driveway.
An issue that you might have with the bumper, even without storing your hoses, is that the rubber end caps sometimes vibrate loose and fall of somewhere on the highway.
If you are not storing anything, you can simply drill holes on opposite sides and insert a couple of small self tapping screws.

If you want to store something in the bumper, you can simply chain the cap to the bumper so you do not loose it if the cap comes off but the contents may still come out.

I made a simple locking pin. Inset the end cap securely and all the way in.
Drill a small hole into the top and bottom and through the inside lip of the cap.
Use a small fine tip brush to paint the bare metal black to protect it.
Cut an old metal clothes hanger to about 7 inches long then bend a loop into one end.
Paint it black.

Simply insert it through the holes, with the loop on top, to lock the cap on. It’s not that hard to line up the wire through the bottom hole (usually).
Unless you were very lucky, or very good, the holes will only line up with the cap turned the right way. You can see if they line up as you insert the cap.
Now you don’t have to worry about whatever is stored inside pushing the caps. off.