Start thinking about it at 1/4 tank and start seriously looking at 1/8th tank. I do carry 5gal of Diesel with me for emergencies but have not had to use it as of yet so just dump it in the tank when I get back home to keep it fresh.
At 36 gallons and 13ish mpg I am ready for a stretch by the time I need to fill up.
The toy hauler does have a 15 gallon fuel tank with pump but its never seen any type of liquid yet. We ride 2 stroke dirt bikes and there is just two of us so I just use two 5 gallon dump cans on our trips and fill those when necessary. I had considered using the fuel tank for diesel and may still but so far just stopping at truck stops or regular stations is fine. I usually go out in the evening after unhooking and fill up the truck before the next days drive and thats fine.
