I would definitely use O3 MAINLY because he's growing in a non-living area O3 would be awesome in space like this, if he wants to grow here he need only be prepared to do some work sealing off, insulating, and some poly sheet in the grow area problem solved ;P. Just be sure of yourself and plan carefully be sure you have the budget for everything you need to start and everything you will need to add over time. I think that is my biggest unexpected challenge got at least a grand into my newbie grow and it's small lol.