When I made the one for our old MH, I used 6 inch PVC and 2 45 degree elbows and a cap on the lower end that was inside by the frame.
I also cut a 1/2 round hole on the top end that was up against the door of the storage compartment. That way the 90 degree end that goes down into the drain stays on and is held in place by the door when it's closed.
Everything stays together and stores together nicely.
Drill a couple of 1/2 or so holes at the low end for drainage also.
Good Luck, and happy building.
2008 Winnebago Adventurer 38J, GP, dozens of small thirsty ponies. Retired after 40 years wrenching on trucks! 2010 Ford Ranger toad with GSXR 1100T or KLR650 in the back. Easy to spot an RVer, they always walk around with a screwdriver or wrench in one hand!