I think that if you can figure out self driving trucks, you can figure out keeping it fueled as well. As a quick and easy solution I would imagine large enough

I think that if you can figure out self driving trucks, you can figure out keeping it fueled as well. As a quick and easy solution I would imagine large enough fuel tanks on the truck itself, and a couple of gas stations with people fueling the trucks at places. One for every large industrial place would already make it very widespread. Another solution would be mechanical arms attaching to the truck.