Getting Diesel at service station or truck stop?

I think the idea of having an extra tank is not for most folks. When you look at the space needed in the box, no camper top on box, the cost of the tank, all the stuff to make it work and the fact that if you carry say 50 gallons that adds over 355# to you load. At 100 gallons it is 710#. Weight equals less mileage. Not such a good deal at all not to mention you need to do a bathroom stop about every 150 miles anyway.