I wholeheartedly agree with everyone who has said to use the SprayMax 2k product. I used to sell automotive paint, and one of the products we stocked (for those folks who came in and didn't have the whole set up) was the SprayMax. The jobber told me that what was in the can was actually Sikkens clear coat, but I was never able to truly find out.

It is simply a 2k urethane clear, just like any other automotive clear. It is reduced with a "normal reducer", so the dry times on the can are for a 70 degree basis. For every 10 degrees you go down in temp, those times should be doubled. For every ten degrees you go up in temp, those times should be halved. Want to get nice flow? Spray on a colder day, the clear won't flash as quickly, allowing it to flow out nicely.

+1 on the safety ideas, too. Mask up and try to have a fan pulling your overspray OUT of wherever you're spraying.

I've had great success going over decals by just shooting a dust coat (light coat) first, let it tack up, and then shoot a wet coat. You can shoot another wet coat after about 10-15 minutes, depending on temp.

When finished, you should be able to sand and polish it after about 7 days. The clear will be cured enough to polish at that point, but a complete "through cure" won't happen for about a month.