Auxiliary tank

[gearhead]

I'm trying to figure out how to have an aux diesel tank and keep my cabover camper. I don't want to spend $1500 for a Titan under bed replacement tank. They don't hold that much more anyway. I was thinking a RDS in bed tank/toolbox combo. But that won't work with the cabover. Told the wife I'll just sell the cabover because I'm tired of stressing over fuel after 2 hours of pulling the 5th wheel. I ran my tank down lower than I want to on our current trip. I do carry a 5 gallon VP Racing diesel jug in the truck bed. I get better mileage with the cabover and can get in all gas stations.
I was just looking at the install instructions for the RDS tank. Not but 3 bolts holding it down. Got me to thinking....when I want to use the cabover just spin those bolts out, plug the end of the fuel hose, and cable tie it to the hold down loop in the front corner of the bed. Slide the tank to the tailgate and pick it up with my engine hoist.
What say you?? Especially those that have installed an aux tank.