Not using high temp paint but using a high temp clear coat doesn't make much sense to me personally. The actual paint is closer to the caliper, and the clear is on top. The paint would get hot before the clear coat...
Also, why not use high temp paint to ensure zero problems with heat? It's kind of a no-brainer. You never know when you'll be in a situation where the brakes will get hot.
I've never measured caliper temps at the track or on the street, but I would think it's always best to play it safe, no?