HOK Designer Pearls question

I was looking at getting a couple quarts of the HOK pearl basecoat for my truck. According to Eastwood's catalog, it says that the pearl basecoats are normally applied over a white basecoat. Would it hurt to skip this step and spray it over a very light grey primer sealer? The catalog doesn't say it must be used but I wanted to get some more opinions.

Thanks,Hmbre97