That's what most people do, tint until desire shade is achieved and then clear over it. Only problem with that is it doesn't stay looking good very long.
I went a different route. I use automotive grade paint (PPG) when I tint the tail lights. Although its more expensive but the result speak for itself. Long term durability and gloss holdout is much better then what spray bomb can achieve. Just ask morcheez about nite shade vs. the tint job I did.
Poonnin