There is a product called lizzard skin that I used on my car. It is a ceramic based paint which a lot of street rodders are using on their builds. It can be sprayed or brushed and dries to a flat black color.It is used for sound and heat control but works well for stone protection. I put three coats on the underside of the body as well as the trunk and footboxes and wheelwells.It works so good most of the time I drive without shoes. Interior stays cool.Look on this site
www.lizardskin.com