Outer Limits 4x4 Board

I have just chopped my wagon and want to make a long range tank for it, I haven't made a fuel tank before but understand how baffles and that work, I am just unsure on the material thinkness. thanks

I made one out alloy for my wagon and I used 3mm and that worked well. what material are you using?

Baffles would be nice. But factory tanks don't have both baffles and neither do replacement aftermarket tanks.
All they have in the bottom is a round bit pipe about 1000mm diameter. With a cut out on the bottom. Stops bait of the splash around the pickup.