My buddy that has the paint shop is looking into it for you. The clear coats out there are not very good for this application. They tend to yellow with heat and are not hard enough and will chip off.
The manufacturers use an epoxy type clear to cause the drying process thus making it much harder. Anything that comes in a can that is dried by air contact that you spray on is not going to work.
He is checking into they kind the manufacturers use and I will let you know if someone else doesn't first.