Thought I would share how I built the bulkhead on my Coleman Xtreme. All parts were purchased from Lowes. Credit goes to Bobby_M for inspiration from his design here
1/2" NPT Coupler
3/4" SS Washer (had to be dremeled slightly larger to fit over nipple)
2" NPT Nipple
3/4" Alloy Washer (cheaper than SS and fit over nipple without modifying)
1/2" Ball Valve
1" CPVC Coupler (1" to 1" female)
For a washer/oring I used the existing white rubber washer that originally sealed the outlet fitting (can be seen in the picks below).
Here is the cooler, and the parts used.
The one part I forgot to show (but shown below) was the 1" CPVC coupler I used as a spacer in the cooler wall. Also, I ended up using an alloy washer on the outside because it was thicker than the SS one.
Closeup of the assembled parts
Getting ready to dremel out a hole that the 1" CPVC spacer will fit into.
I used a chop saw to cut the 1" CPVC spacer to the right height (just flush with the outside of the cooler). The spacer prevents the thick (foam filled) wall from collapsing when you tighten the bulkhead.
I had to notch the SS washer because the factory hole Coleman drilled was not centered. The notch prevented the washer from resting on the curved side.
It passed the leak test with flying colors.