If you completely remove the airbox you will need to make a couple brackets anyway. The bottom of the airbox also acts a a mudflap for the rear wheel under the seat, no airbox and you'll get everyhting under the seat all f'd up quickly. The box also acts as braces for the faux side covers so you would need brackets there ot just leave the side covers off.
When I had the Mikuni carbs, I ran it with no side covers and it looked like someone vandelized my bike. It looked odd without anything there.
You could aslways chp some of the airbox away, but I'm not sure how much you really need to leave intact for brackest and structural support.
Give it a try, there are lots os airboxes available for cheap.