Extra gas tank...

Hey guys, hope everyone is doing well.
So this is basically what i want to do... i want to have an extra gas tank in the bed of the truck but i want it connected to my main tank. Gravity fed or pump fed or something, im not sure. I remember doing some research on this awhile back and there was someone that did it. I found someone here that does but mostly here locally everyone works with diesel. They say with gas i might have codes pop up for ventilation or something. Like i said, this was sometime ago. If anyone can point me in the right direction or any better ideas lmk. Thanks.

Ps. Yes, i can just have jerry cans...but that's not what i want. Thank you.

 

https://www.transferflow.com/shop/product/0800116206

FYI In the USA you cannot legally connect them, it is either a spare tank, or a larger
tank replacing OEM under the vehicle.

 

Just cause it's illegal doesn't mean no one has done it. And the legalities o of it are unclear. There are certain ways to do it right. Shut off valve, ventilation and other things.

Btw, next time use lmgtfy.com. it's funnier but thank you though for the help. Any help is better than none