Discreet fresh air intake

I have two 10x10x7 tents in a large garage and I was looking for some ideas on how to discreetly bring fresh air into the tents to cool it and provide co2. I was just going to have the fresh air dumped into the whole garge and then have the tents intake the fresh air from there. The more discreet the fresh air intake on the exterior of the garage the better, i was thinking somewhere up by the existing vent holes in the attic but was skeptical on having it up so high bringing in warm air. I attached a couple pics of the exterior are where i was considering bring in the fresh air and the attic as well. Thanks for any help

I'm actually in the middle of this right now.. I ended up buying a speedi-duct boot from HD and am going to make a new register in the living room. The parts just got to the house today. I have new register go through the attic into my veg tent tees off coming out goes through 2 rows of lights (2x3) in the flower side then tees back together to go out into the attic. Last summer I was up there rolling insulation and it was 127 degrees. Too hot to pull through my lights imo. I'll just buy 2 new register faces so they match and no one will ever know. It's all 8" and has 2x8" vortex fans to cool 4800w of lights. You can just flip the fans around in the winter and heat your house haha.

So from the living room, into one side of the tent through the light out the other side of the tent the split ending up to exhaust in the attic All sealed mini-split 10 burner CO2 etc etc. My dads idea to make a dummy register in the living room for cooler air than use the attic or using outside air haha.