+1!

That looks like a slightly more elaborate set-up than I've used for bike frames.

My favorite was very similar, but in a single car garage. The back door was intake and I had 3 similar fans for exhaust. I just set them under the bottom edge of the roll-up door.
I only used the $35 charcoal respirator, inspite of it's limitations with isocyanate paints.
Thing was, I had so much draw from the fans, I merely stayed up-wind of my spraying.
If I had to go down-wind, I held my breath.
I had a plywood panel with filters for the intake door and used suction to hold the filters over the fans.
So yes, I sprayed paint pretty much right near the fan motors.
No explosions.
I guess the airflow was such that it couldn't concentrate at all.
Plenty of mondo extingqishers at hand though.

Another +1! for wetting the floor! I use a 2 gallon plastic pump garden sprayer. Usualy used for fertilizer/insecticides. DO label it for WATER ONLY.
If you use sheets rather than 6 mil plastic, wet that with the sprayer too.
Minimizes dust AND fire hazard.

and remeber...don't sand metallic or pearl colors and
..on the final coat of clear(or single stage color)
do a fast wet coat with slow reducer.
The "trick" is to have ALL the paint be "wet" at the same time.
With out runs or dusty spots.

Runs; too much paint. Flip the frame to help smooth it out as it dries.
Dusty; not enough paint. Spray lightly with JUST reducer to help blend the dust out.

If you get nits in the final coat, just let them be. Fishing out that spec of dust will be far more trouble than polishing that tiny spot when the paint is hard.
Gnats are the worst! Once they land on the wet paint, they just roll over to die.
You can get the body, but the wings are THERE!

One of the Brent Steelman frames I did had a perfect set of wings on the chainstay.
Brent didn't like that much.
(I was going to go ahead and leave the body for that Jurrasic Park effect.)

Anyway, gotta run.
Good luck with that c-kid!

Dr. D