I have been airbrushing murals for a long time on new paint that needs cleared. I am now getting into murals on cars that are already painted and have existing clear. 1)After I have scuffed the old clear and painted my mural how can I be sure the clear I am applying will match the existing clear in gloss on bordering body panels? 2)and should I only clear where my mural is or do I need to clear the entire panel so it is a consistent finish? I don’t want to be responsible for messing up someones existing paint job.