sounds like a good idea Allan - maybe you could also consider removing wind-induced mount wobbles if you drive the shutter based on how much signal you get from an accelerometer on the scope?
downsides might be that the shutter would always be reacting after the event - wouldn't be fast enough to do the job with quick disturbances. The shutter will wear out quickly, but that may not be a deal breaker. Maybe a separate liquid crystal shutter would be an idea - faster and longer lasting. Also, the longer sub length will add to the dark current, but again, probably no big deal.
let us know how you get on
.