Hughes Auto-former/Surge guard

Well, after many years of having both in my arsenal, I'm finally getting around to installing my portable units inside the storage compartment. In all the years I've had the 50 amp autoformer, I can't say that I'd ever noticed it Hot but they do suggest to mount it in a ventilated compartment? I'm not worried about having to make a vent hole in the fiberglass but I'm looking for some real world experience as to whether it actually needs that or could I place a whisper can close by and keep it uncrowded in the area I put it?

I guess my only real concern making a vent hole is weather incursion into the storage area but I think most vent covers work well or I could get one of those shiny dryer vent covers.