One car was my Lotus Super 7 replica, and it was at the back of the frame near the tank. I autocrossed this car on slicks, and I wanted to run as light on fuel as I could without starving the pump.
One was my '77 Silverado, and I tucked it inside the frame rail just ahead of the dual tank switch, with an AC Delco electric pump feeding it, and a Ford F150 pump drawing from it. This setup was cheaper than buy two EFI tanks and two EFI pickups and two EFI pumps.
On my V8 Pontiac Firefly I built the fuel tank with a sump inside that WAS the method for fuel to get from the left to the right side of the tank, in the hopes of limiting starvation without running a second pump.
I usually make them about a liter in volume, I'm not sure there is science behind it. The best is tall and narrow, so the outlet is always covered with fuel.
There are a number of aftermarket manufacturers that have a "Fuel Center" which your low pressure pump fills, and a high pressure pump inside does the rest. I have not used one, so I cannot speak to how awesome or wretched they are.
example:
https://www.summitracing.com/int/par...0003/overview/
My plan on my '61 is get an EFI Suburban tank and run it at the back.