I believe the light is a Sunboard
I have a couple and they work great
I liked the sunboards better than the QBs just for the reason they run on 36 v, like my diy cobs
But sadly, it does appear he has shut down.
What. k is your board???
I’ve a wardrobe like your ( old n all) but double the size (2doors)
Had a 4K sunboard in there and it kicked ass.
Don’t know how stealthy you are aiming at) but My thoughts are your fan , while it may work will not push through a carbon filter.
You’ve more than enough rooms for a 4 inch inline fan/scrubber.
Good work!!