Well , got under the truck and look at the gas tank idea, looks like if I wanted to make a larger main tank I can go forward a foot or so, will have to go around the wiring connector that under the body but can do it. If I made a different tank would most likely us the stock tank straps, that make for more work in making the tank , but not a big problem. Can't go any farther to the rear, will hit the rear end. The rear tank idea is easy pull the spare make a tank that will fit in the space , will need to fill that and can use the stock fill setup for the front tank, but will have to put in a second fill door. Cut one out of ranger in the junk yard , no big deal except for the repaint of the bed , not a major problem but more work, and how many people want to repaint the bed side to add a second door??? Never engineered a gas tank before ,made them, but the idea of a shallow flat tank having problems , never thought that would be a problem. So what to do ? If I had an extra tank to play with that would make things easier, could figure out how to make the pump setup work and get the breathing of the tank correct , will look into how much an tank at the junk yard would be , if I go on 1/2 price day that would make it cheaper, but still like the idea of a large flat tank in the bed of the truck and make it the new floor of the truck. Could fill it from the corner of the bed and have it gravity fill the main tank, no pump required, and could add as much as 75 gallons , easy. Want to have a larger tank so can have a much farther range if or when I need it, will stay on it.