That's f#$%ing perfect! It's pretty much as I had envisaged fabricating. Sooo much easier to use off the shelf parts.
I think it will be better without the white vent cover and with a fabricated duct.
A regulated 3V (from "12V") is almost trivial to achieve.
I'm also thinking an aero profile on the blocking slats for when they are open
.
And, can something useful be done with the timer/clock?