Grit dog wrote:
If any of these other options aren’t feasible for some reason, you can make a storage “tube” out of pvc with a threaded cleanout cap on one end and mount it under the trailer.
Ours came with this :)
To the OP, I also suggest that in addition to the hose, you get a plastic bucket (I bought mine at the grocery store, it's a cheap 3 gallon one), and put this under the cleanout to catch any drips when you open it prior to putting the hose on. In that bucket we also keep a few rags, some paper towels, some rubber gloves, and Clorox wipes.
The bucket came in handy on our first dump on our last rig. We didn't realize it had a second gray tank valve (this won't be the case with you), and when we opened the cleanout, gray water starting pouring out. We were able to get the hose on pretty fast, but the bucket was able to catch most of the water before we got the hose on.