I have no idea about this subject because I've never done it but I do have an opinion. With the concern of being rear ended as with any truck camper arrangement the camper is going to be crushed if it's a high enough speed to ever worry about it actually being pushed forward, I would think these gas tanks that I see all over the place could handle such an impact as they were built specifically for the front of the pickup. I've seen them in every work truck configuration there is from landscaping to building contractors. I don't know the specs of these tanks but I imagine because of DOT rules they are hunkers of a tank. As far as the camper being shoved forward, that is going to be one hell of a rear end hit and the gas tank would be crushed and punctured as that is how they are designed on cars as well as being pushed forward into the cab. Would this kind of accident happen while moving? doubtful but standing still yes, but with the shear force of a rear end hit like that the truck would be pushed forward as well. With a rear accident of these proportions I would think anything would come into play including casualties from the hit itself. To be rear ended at a stoplight with a driver not paying attention at 65 MPH the aux tank is just going to be an added problem not the problem. I would not be concerned with this rig setup.
