Hot rod flatz makes a single stage paint. I have already used it on my for the roof, inside cab and dash. Adding a matting agent to clear is one way but not always the best to keep that same low % gloss for every panel. There products are not pricey at all and they have "primer" colored paint . Kustom shop.
After dealing with the other way to get flat color on the bikes this is the only product we use now. In fact a local extreme high end car shop that is in tons of magazines came by to check this product out. It is easy to use and looks the same panel or tin are tin..
I would be happy to take a few pics if you want , in the light the flat pearl metallics really pop.. I know the name and what they are does not add up but it is what it is..
http://www.tcpglobal.com/kustomshop/ksflatz.aspx