Electric fuel pump question

Hi all. I am getting a car ready for a demolition derby. Usually I run something older with a chevy 350, but due to time constraints I am stripping out a 89 mercury Grand Marquis with a 5.0. It runs and drives, so it won't take long to get ready. Anyway, I am having trouble figuring out the easiest way to do the fuel system. Normally, with a mechanical pump on the motor, no problem. Fasten down an outboard 6 gallon tank, run a fuel line to it, and all's set. But on this car, I need to keep the stock electric pump in the tank in use. Does this pump have to be mounted inside a tank, or can I mount it externally out in the open? I was looking at it today, I could take the pump off the sending unit, take the sock/filter off, mount the pump on the floorboard, and run a line from where the sock was to my small tank. Would this work? I see three choices to make this car run....First, do as I just described and mount the pump externally on the floor. Second, if the pump must be inside a tank, I could cut a hole in the top of my small tank, and mount the complete stock sending unit with pump in the tank...a lot of work, and i'd still have to modify the unit because it originally mounted on the side of the stock tank so I would have to do some cutting/welding/bending to get the angles right inside the little tank. Third, if the pump has to be inside a tank...I'm assuming it would be to cool/lube the pump... could I mount the pump in a seperate gallon-sized jug of water, and then run my line to my small tank? This way I wouldn't have to modify my small tank, I would just have an extra small tank of water mounted next to the fuel tank. Any ideas or comments are greatly appreciated!! Earl