Might as well weld in the mount for the propane tank now while it's easy to get at.
That's as tucked up as it'll go while still being accessible for filling.
Hangs as low as the bottom of the muffler. We'll see.
The other optional position was forward of the rear bumper between the frame rails. That would impact the departure angle too much so it goes back of the cab under the front of the box.
