Never tried US Composites myself, but… usually a phone call will speed up the process.
I’d recommend buying tooling gel coat in smaller quantities. It’s got a limited shelf life and in your climate it may be even more abbreviated anyway. Unless you have a refrigerator dedicated for your shop. Check out http://www.fiberglasssupply.com/Product_Catalog/Gel_Coats/gel_coats.html They have quarts of both black and orange for around $30. Gallons are around $60. Don’t know how much shipping would run. At any rate, I get very good service from them and since they’re out west (WA) shipping should be relatively quick. The smaller quantity may make it under the hazardous shipping radar… Also, fiberglasssupply sells quarts of duratec hi gloss clear! I know their website isn’t very fancy and ordering is more difficult, but it is a price I am willing to pay given their customer service and low prices.