I would paint the whole car with the same paint. I did the same thing your painter is talking about to my Challenger, base coat clear coat on the body and single stage everywhere else. I didn't like it. The two different paints didn't match very well and the single stage wasn't as shiny, almost looked flat next to the clear coat. Also the tape lines were pretty obvious and the two paints aren't compatible, like if you need to go back and touch up something make sure its the same kind of paint. I'm doing another car now and I will be doing base and clear on the entire car. Mine was yellow too.