I grow in a closet…..it’s smaller, 2’x6’ with an 8’ ceiling. I have an attic opening just like yours. I run a 4” exhaust fan directly through the attic cover…and it works great.
Before you make any moves, you’ll want to identify what, if anything, is in the attic. In my case, it’s an empty, uninsulated space that has air vents open to the outside. So there is nothing to ruin.
You don’t want to be pumping a ton of moist air into a closed in space without considering its effects.
If it were me, I’d just grow in the open closet…..but that’s up to U.