I've been painting as a hobby for almost 40 years. My favorite single stage paint is dupont centari. With a cross-linker hardener it cures over night and can be wet-sanded and polished the next day. Mar-hyd high-gloss hardener works great and is half the price of the dupont stuff. You tailor the reducer to the temperature, but certainly should be 72 or so or above, up to about 85. Heat lamps or a heater will accellerate the curing/drying process. The solvents evaporate pretty quickly, like tack free in about an hour, and the hardner is a chemical process that continues for a few weeks. Centari is so hard that once it's set up hard is quite difficult to polish. Should be done while it's still soft, like next day. That's always how I've done it and my paint work comes out like glass.

You can't buy centari in calif any more due to the idiots at CARB. But you can still buy it around the country. Hands down THE BEST single stage paint money can buy.

For a carb compliant paint their chroma-system also works very well, but costs 3-5 times as much. Dupont has a budget line under NASON that works quite well but the color matching is horrible. It's fine for an overall or a complete panel, wheels, rockers, etc. Just don't try to match anything existing. And it's really cheap, holds up reasonable well.