nice idea rives,
Ive thought about doing something along those lines but It would have to be air tite.
I'm sealed w/Co2. and venting is an issue which 1 reason I'm sealed.
Q for ya... how long can i run a cord from the ballasts to the lights?
and again from the outlets to the ballasts, ive read some digi's have 50ft cords to lamps... maybe??
I'm on 220v if that has anything to do with anything
Being air tight wouldn't be an issue, most gutters seal up pretty tight and they make (for a premium) gasketed versions that are very tight. I don't know what the cord length could be for the MH family, but I would think that it could be pretty long with the possible exception of the pulse-start family. As far as I know, that is the only issue with remote-mounted HPS - the leads can be very long, but the ignitor needs to be moved out near the lamp when they get excessive.
The voltage to the lamp doesn't change based on your input voltage.