There's more than one way to limit the amount of fresh water that the toilet uses. It's not a big deal if you're paying for a place with water and sewer, but if you're set up in a beautiful meadow there's no sense wasting water. I've heard of people installing them on the supply line under the vent tube or on the supply line in the back corner of the closet, but neither of those locations resonated with me.
Since I was in a plumbing mood (i.e. all the tools were already in the trailer) I figured I'd keep going. Working with the PEX (Poly Ethylene Cross Linked) plumbing is very easy and made easier by fittings that don't require special tools to retain the hose on the barbed fitting. It was even easier because my local Ace Hardware stocked the Flair-It brand fittings.
I decided to cut the supply line near the vent and then carefully rotate the section connected to the flush valve so that the cut section was vertical. I drilled a new hole through the bathroom wall into the closet and installed the valve and elbow assembly onto the vertical line to the toilet valve. The old hole through the wall was filled and sealed with silicon.
Added a section to connect the supply in the closet to the new higher location and then pressure tested the whole works. Now I can sleep at night, even when we forget to turn off the water pump. And it's easy to reach the valve when you want to turn it on.