This is what I use...mounted it to my trailer and fill up at the last gas station before I get to the track. Youll also need the filler hose which is another $10 I think.
If you need more and are at the track you could always put the fuel jugs in your towing vehicle and drive to a gas station during lunch.
https://www.amazon.com/VP-Racing-Fue...acing+5+gallon
https://www.amazon.com/Fly-Racing-52...s=fly+gas+rack