Even though OP has decided not to go this route, I am going to second the pictures request. I can remember seeing an in-trailer system at a club race not long ago that had an exterior hose on the trailer. It was like a gas station for race cars. Anyone have any pictures?

 

I recently ordered an InTech trailer and asked about an onboard tank for refueling the race car. I learned that the tanks offered are not very large (maybe a max of 40 gallons?) and their intended use is refueling of the generator.