[davepl]

Can you tie them together at a low enough point to be useful and still be safe though? Fuel doesn't flow uphill, so the line needs to be the lowest part of the tank (or it'll be the lowest point at which the two tanks will exchange fuel, anyway).

I worry that having a line come out of the bottom of one tank and into the bottom of the other would be so low that it'd be hard to route safely. But I can't read your mind or see the tanks, so just throwing it out there.