Use an FPV video camera instead. You can use your iPhone to convert the video images to stills. As long as you are not flying this should be legal. The only question is the legality of using RC cars for commercial purposes without a license/permit. I wouldn't know who to ask about that but you could try the FCC. Again, as long as you are not flying you aren't running afoul of FAA regulations.
My comments assume you are in the United States since you don't give your location.