I used the plastic Buyers Item# 3480311
shown on that link:
I've put the box on 2 short 11 pound propane
tanks and the battery
. The picture shows the first attempt, I'm on revision 3 now but the location is the same. The box is slightly ahead to allow the lid to open and/or access to the propane
valves. The box actually locks the propane
tanks in. It is set up so the entire box can be tilted forward like a cab-over on a big truck to get at the battery
and propane tanks. It is used to store light
bulky thinks like the plastic wheel chocks, the trailer jacks, the water hose etc. while travelling and converts to a lockable storage for when we are camping.
In the picture on the right it looks like the box is real close to the truck, but that is not the case. The truck is turned to the right by at least 45 degrees hiding the hitch. I know I can get close to a 90 degree turn and still be clear of the box.