There are some newer acrylic enamels on the market that use 601 reducer and are high gloss. I think car quest has one that is a tractor paint in many colors. it has the hardner in it and is less than $40 a gallon. Works good in a trunk, under a hood et. Is tuff and looks decent. You could even run it out too..
Single stage paints don't need a clear top coat,but some do require a hardener just look at mixing instructions on the side of can it will tell you what you need.