I came up with a modification using a car door lock actuator ($6) and plumbing valve, some small copper pipe sections..hose..etc to make a power vent that can be operated from the cockpit.
The actuator triggers the valve to open and close (via a momentary DPDT switch in the cockpit)
I also added a magnetic switch to trigger a siren to ensure I remember to close the valve
Let me know if anyone has any questions or comments.
All the pictures are here:Power Ballast tank mod
some samples:




