with the inconvenience and what it will cost to run out of gas 1 time, it would be wise to buy an "in-bed" auxiliary fuel tank... they come in many configurations and options for size, with/without tool storage boxes, and you have a few options on how you get the fuel from it to your main tank.... (manual pump, electric pump, vacuum pump, direct connection with a manual or electric valve, ect)....
and the best part is, with the right size of tank, you dont need to rely on a fuel station within the range of a couple of tanks of fuel....until you use all the fuel out of the aux tank.
I built my own and have it direct connected into the filler hose of the pickup, and use a lighted electric switch to control the fuel transfer to the main tank.... my pickup tank holds 40gals and my aux tank holds 90gallons of fuel, and when im getting low driving down the highway, I can flip the switch and let gravity fill my tank.... and shut it off when its full.
with the EPA style caps that are used today, there is NO worry about running the tank over and spilling fuel if you forget to shut the switch off in time. it gives a great range before needing to stop and refill.
I have added an electric pump so that when running with someone else I can transfer fuel to them, so we dont have to worry about a fuel stop in remote areas when we want to push on for a few more miles..
Ive been using this same set up on the last 4 pickups Ive owned since 1979...