Thank you all for the good advise and idea's.

Sean

You'll definitely want at least a mechanical backup for the valve if a
full tail ballast can put your C of G really aft of the normal range.
(I have flown with an overfilled tail ballast through sheer arrogance
and wouldn't want to repeat that.)

The Schleicher valves are notoriously prone to problems with the
connectors and almost all other parts of the system and a blown fuse
gets you zero volts which is less than the required 5V... (I have
flown an ASH25 full of water where one of the valves didn't open and
wouldn't want to repeat that.)

Do yourself a favor and copy one of the mechanical systems.