I made this sewer hose system using rain gutter parts. I bought 2-10' pieces of 4'' plastic gutters and cut them so I ended up with a 6' and 4' piece from each section.
I can go anywhere from 4-18'. I first hook the hose up from the outlet to the sewer inlet. Then I place however many sections necessary of gutter under the hose. The section that starts at the RV goes on top of the downward section. I overlap them by at least 3-4".
Then I put a gutter drop outlet, left, in the picture below, under the gutter where the sections overlap. I added downspout couplers, right, in the picture below, to raise the gutter to the height necessary for flow.
I used bungee cords to hold it together. It looks like the image below. I strung the bungee cords under the gutter drop outlet and hooked them together at the top of the hose. (Below)
Each downspout coupler adds 2'' to the height. I can use 1" x 6" boards under the gutter drop outlets to tweak if necessary. I am using this in a long (17') run right now in Needles, CA where we are experiencing 25 mph winds and it has stayed upright.
It may have been done this way before, I don't know. Thought I'd share.