You want to consider Braking Power. Hauling weight demands a lot of stopping power. Flat land you might get away with a 200 Gallon tank if you drive careful IMHO. Hill country go with no more than 150 gallons.
F150 are only sedans with a bed on the back. What you need is a real truck which start at 3/4 ton rating. GVW is calculated by the Braking power.
You can lead a Donkey to water but you can't make the Jackass Drink
"As Americans you have the right to be stupid." John Kerry
"Life is tough, but it's tougher when you're stupid.” John Wayne.