Most RV units, the bumper is the typical home for the Sewer Hose. My last trailer that's where mine was in the square bumper. Don't know how many times I nearly lost those friction fit caps. Finally bought two bumper covers that screwed in and had a hinged lid that opened and closed.
Some people take a piece of PVC Pipe and attach to the bumper, or underneath the unit. Works well but personally I don't care for how it looks.. Just my opinion no offense to those that have them. Also with a toy hauler I didn't want a PVC pipe to get in the way of rear door workings...
So I bought a Sewer Hose Door at a local RV Parts place. Cost about 15 bucks. I then took a 3 foot length of 4" flexible but rigid metal ducting (I had left over from my upgrade on the RV basement to bedroom furnace project.) I angled it to the left and capped off at the end. I drilled drain holes into it so any water would drain.
I measured down on the skirting and lined it up with the water fill door. There is an airspace in my unit below the floor & frame. There is nothing in there it has the curved skirting all around to make it look good and line up with the frame on the bottom . I carefully drilled an opening and then used several screws provided with the door to secure. Topped off with Chalking around the entire door. I'm happy with this install sewer pipe fits in and comes out easily and it looks like factory install. I just need to locate a sticker for the door and it will be really slick.
Total install time, about a half hour. I think it's well worth the effort and for me it's in a spot thats convienient to get at when I have to dump the grey and black water!