Chili
Explorer
I ended up putting them right next to the water tank. So, rear / right third ish. Looks nice and clean there as they're about the same size as the water tank. I have limited space in my apartment so my plan is to keep them up on the rack permanently, empty, and locked. Then, when I go on a trip, fill them up. If I don't end up using the gas, I'll use a siphon to fill up my tank at home so I'm back to empty and don't have stale gas sitting around.
One other recommendation I have seen for roof mounted cans is to top off your vehicle tank with the rooftop fuel as soon as there is room. Don't wait until you are close to empty, just wait until you are down enough to accept the can contents. That way the weight is only up top when absolutely necessary. Basically adding to ar4me's post.
I do not have a mount for mine yet, but have considered the roof since I am ditching the trailer and don't have any other place for them on the Jeep