you do a really high roll up vent, you don't need an exhaust for when it's open. If you keep the blackout time short, you don't need an exhaust at all, but it's cool to have a small one to exhaust moisture. A 10" inline will work. A 24" shutter is better. If cost is an issue, i would get horizontal air movement fans first.
The thing about shutter fans in blackout is you need something to block light. Light traps can be pricy.
If you have an auto depp you can just black out for a couple hours at night, open back up, and a couple hours in the morning. U don't get any mold.