Its a great idea except for what stdave66 pointed out.
Plasma/weld exhaust torits have a hard enough time not smoldering into flames the way it is.

Ive seen several where I work smoke it up. The filters would be a good idea, but certainty wouldnt catch everything.
You could get by with doing exactly what you are thinking, except use a separate fan, and simply stick that fan in the back or your box (booth), throw in some filters, and have at it. It would be a good idea to use an explosion proof fan. But between you and me, ive used a box fan many times without a problem.... Unless your spraying nitro cellulose laquer.

You want it done cheap and fast, it wont be right.
You want it done right and fast, it wont be cheap.
You want it done right and cheap.., come back in a year..