Limitations/Difficulties of Chameleon/Mirage Paint

I am trying to figure out what to do with my car, and a few ideas came to me (maybe not good ideas, but ideas) involving color-changing paint.

I was considering keeping my car purple and adding a purple/green racing stripe along the top, but is it a Bad Idea to just use that spray stuff (I'm doing it myself, can't afford to pay for the real thing, and don't care if it's not showroom-quality or anywhere near) on top of the existing paint? Basically, what I'm asking is, is the sanding necessary to keep the stuff from flaking right off the car? I don't want to sand the paint off the car because [I'm a bit lazy and] there's no way I can use a sander to get it down to a perfect line without going back later and doing SERIOUS touchup on the old purple (or is there?). This is just for fun, not to really impress anyone right now.

Judging from my limited research, I figure there isn't a way to get a clear/green color change so that it gives a ghostly green stripe effect, or is there such a thing that I just haven't found?

How about some vinyl graphics?

How about some vinyl graphics?

Do they make color-changing vinyl? If the chameleon paint was out of the question/too hard I was going to go with a green vinyl stripe anyway.

I dont know.