I also replaced the hard PVC pipe that the flexible hose fits inside. Bought a new one from hardware store as mine had crushed a bit. The new pipe was thicker and stronger so a tight fit but easy to do. I had been worried more serious pipes had froze and broke when I had white plastic chunks fall out the back!
1) If your grey and black tanks are empty fill them with fresh water and flush both tanks out well. You will be more comfortable working under the van.
2) drive wheels onto a few 2" x 8" boards cut about 2' each to lift your van and make it easier to work under. I use at least two layers of the 2 x 8s under the rear tires. Place some scrap carpet to lay on and wear safety glasses to keep anything from falling into your eyes.
3) with a screwdriver or socket wrench loosen the hose clamps that hold the hard plastic pipe to your van.
4) twist the pipe with pressure to the rear and it should slip out even if tight.
5) now you may twist off (counter clockwise like a jar lid) 1/4 turn the fitting for the flexible hose and find a replacement which fits into the hard pipe.
6) If you bought a new hard plastic cover pipe cut it the same length as the old one and press on a threaded fitting to screw in the end cover. You might use plastic plumbing cement but I did not bother because it will not be under pressure.
7) slide the new hose onto a fitting that attaches to the van. It is a tight fit so twist in the direction that the metal wire 'screws on' and it will stretch tightly on then slide more on working bit by bit around the fitting.
8) twist the fitting onto the van hard pipes then slide the hard plastic cover over the hose.
9) re attach the hard plastic pipe hose cover with the hose clamps to the van.
10) trim any hose that does not squeeze into the plastic cover by cutting the hard wire first with wire cutters. I bought a heavy duty 15' or 20' hose at wally world I think which mostly fit.
11) push the hose into the plastic cover and screw on the end fitting.
Spend the next weekend on the beach or mountains.