OK, I'm sure this has probably been discussed before, or even achieved. But, I had a thought... Would it be possible to keep the stock gas tank and use it as a filler for the new tank under the bed? Are you with me?
I'm thinking, instead of adding a fill spot to the bed somewhere - keep the tank behind the seat. Run a line to the new tank as a filler hose, either gravity fed, or with an external pump (which I already have). This way, I could fill up the stock tank as always and let that fill the new tank under the bed and supply the fuel pump, basically as an auxiliary fuel cell. I get the benefit of having the baffled tank with the new equipment to supply the motor, but also a longer range due to the extra tank. Also, I won't have to fab up a fill location in the bed for the new tank. Does any of that make sense? The hose size from 1 tank to the next would probably have to be larger than what is already there, now that I think on it more. I was hoping to just use the current size coming out of the stock tank. Convert it to a hard line to keep it from sagging, or re-purpose the stock hardline to run to the back. Or, just use steel braided line and keep it from sagging too much - keep the low spots out of it.
I don't know... sometimes I overthink things, or get accused of dumb ideas - maybe this is one of them.
What do you guys think? I'm sure if it worked, it would be talked about a lot more on here.