Waterbug_wpb,
I think yellow would be the colour that best fills in your stated requirements.

Ever tried spraying yellow on a boat, I assume it would be the same with yellow gelcoat.
It is difficult to get a good and consistent colour. You end up using a lot more than you would if spraying white.
I don't know if it does but it should cost more.

Regards,
Phill

I know that the voices in my head aint real,
but they have some pretty good ideas.
There is no such thing as a quick fix and I've never had free lunch!