There's some long stretches of road in Central and South America where gas stations are few and far between so we decided we need a jerry can. The tricky part was figuring out where the hell to put it and how to mount it.  After consulting the photos of the bare camper frame that Four Wheel sent us, and much measuring, we figured we could get it to fit on the rear passenger side of the camper.  This thing will weigh close to fifty pounds when it's full, and we'll be bouncing around on rutted bumpy roads. I really wanted to make sure it was on there as securely as possible.  There's two vertical framing members on that side of the door which just happened to be an appropriate distance apart for the holder that we got.  Then on the inside of the camper there's plywood.  I drilled all the way through and used 4 1/2" x 1/4" bolts with some washers and nuts to secure it.  The exposed bolt ends come out in the space where we store our toilet, so it took quite a bit of measuring to make sure they didn't run into it, but in the end it worked out perfectly.  I'm able to put my entire weight on it and it doesn't seem the least bit strained, so I feel pretty good about it standing up to the rough roads.