How is your hood like?
I'm running an adjust a wing with a 400W hooked on it, all in a 120x80x140 homebox (the twin with upper veg room) only cooled by a Vents TT125 extractor running on low speed (220M3/h) and it works well.
In fact, it does way better than with my cooltube : the bulb isn't cooled itself anymore but the heat is spead over the reflector, better footprint also.
It also depends on how your ambients temps look like. The room where my tent stay is around 18°c now, thanks to the european shitty spring