I've done exactly what you describe, except:

- No plastic on the floor. It's a pain in the butt, and you don't need it if you thoroughly clean the floor.

- If you're using the fan to draw air out of the room, the fan motor better be explosion proof - or you'll be sucking fumes right through an electrical device. I moved air INTO the room, creating a positive pressure, and let it vent naturally

- All spark or flame generating devices in the room need to be shut off, or isolated. Your compressor, for instance. Water heater pilot light.

- You need plenty of light, and if you should slip and break a light bulb, bad things can happen. Light bulbs should be outside the poly, or have a protective screen.

- Use an HVLP gun to cut down overspray.

Even with all these precautions, any small spark can have serious consequences. Particulate explosions are not pretty.

I'm concerned about this myself, and am still trying to figure out what I'm going to do. I knew a guy who was painting an upstairs bedroom, and blew the whole front of the house out. He got seriously burned also.