I recently replaced my "Stinky Slinky " with a Rhino Flex sewer hose and the large end doesn't fit my 4 inch bumper which I found out is 1/4 inch smaller than some other 4 inch bumpers. After seeing the excellent carriers by John and Kitty I finally settled on using 5 inch plastic fence post from Home Depot. Lowes shows a 4 3/4 inch post on their website but didn't have any in stock. HD also had a nice looking post cap for the post, cheap.
A 1 inch wood bit made a couple of nice finger holes in the cap and cut cleanly through the plastic. To hold the cap in place I used a 5/16 by 6 inch carriage bolt. I used a grinding wheel to put a bevel on the end to make it easier to drop in the slot and ground a ring on the bolt to hold a "hitch pin clip". The hitch pin clip shown here is an "Ergo Clip", it was on clearence at Lowes. I think a wooden spring clip clothes pin would work too. The 5/16 woodworking bit made a clean cut in the plastic for the bolt.
I played with a few ideas to hold it to the bumper and knew I needed to raise it to clear the u-bolts that hold the spare to the bumper. I attached a 3/4 inch thick block to the post, near the ends, with pop rivets thinking I could tie it to the bumper. After I did that I decided to use a T-bolt and 1/4 inch hex cap screw through the post and bumper. That required a 5/15 hole in the bumper and a 1/4 inch hole in the wood block and post. It holds everything secure and doesn't intrude in either the plastic post or the metal bumper and makes for easy removal for cleaning the back of the camper.
I have a collapsible carrier for the sewer hose when set up but also carry a few pieces of thin wall PVC sewer pipe, cut in half, for longer runs. They make a nice slide out tray for the hose and fit nicely in the 5 inch fence post.