Nice three year old thread bump...but anyway...
In general RC car bodies are made from clear lexan and are painted on the inside, this will mean applying the candy first and no laquer will be required.
I take it you are painting a boat? In this case, yes you would paint it on the outside meaning you would apply the silver groundcoat first.
Also worth mentioning that the amount of candy you apply will affect the tone and effect of the colour, I recommend you try a few test panels....start with 3 coats of candy..anymore than 6 is usually pointless. Oh also vital to apply each coat of candy evenly...spray with the correct pressure for your gun set-up and thin the paint to achieve the correct viscosity.
Good luck and be sure to put some pictures up.
