I'm not a big fan of clear coats over gelcoat.
Where clear comes in handy is for years of polishing. When you buff with a machine, the oxidized material tends to swirl around with the compound. When you cross over colors - let's use red and white - the red material gets in the pores of the white and vice-versa. So, when buffing clear, it is all the same, even when you cross over. Makes for a nicer finished product.
It also adds depth, giving a shiny layer on top of the color. Same as on your automobile(s).