I'd love to know where you located the pump and where it discharges.
The previous owners of Indigo installed a secondary bilge pump similar to what you are thinking. It consists of a Jabsco pump with a small diameter clear hose led under the fuel tank, a small strainer, and a simple on/off switch. It works great and has kept our bilge dry as a bone under the tank (we just pulled the tank a couple of months ago). I also threw an absorbent towel (like a sham-wow) in the bilge which catches most of the drips before they can run under the tank. When i suspect water in the bilge I flip the switch and let the jabsco pump out the water. The clear hose makes it easy to see when all of the water is expelled. Highly recommended.