Pumping out a flat bilge
Rule pumps make automatic bilge pumps. Instead of a float switch these have an electronic chip that turns them on periodically for a few seconds. The chip then senses whether there is water flow (I think by measuring current to the motor. Higher current means it''s pumping water). If there is flow the pump stays on. If not, it quickly shuts down.
Here''s Rule''s web site for these pumps:
I think the test run current is small averaged over time and with a half gallon a day may be well worth it.
You still have the problem of having enough depth for the pump to suck on but maybe with a short remote pick up tube it might work. Don''t see any at Sailnet but I think West Marine carries them.