Pat,
I assume there's no need to finish sand before the clear coat....no need to blend seams. Water colors are so thin there is no ridge to speak of.
A couple years ago I got Createx water color kits (2 of them, solids and fluorescents) but have not used them much. Just one rudder. A totally different technique is required of course. And I'm not sure I got it right. But it is very light and opaque enough. Have you tried Createx and what were your results?
All of my stuff is done with solvent base not water base. You have to be really careful on the seams (overlaps) if there is any candy (which I will cover) or blending any sanding will just take it off. There are ways to deal with it which I will cover as well.
Createx is good stuff, but I have never worked with it. I do work with water base for photo realistic airbrush work. I use E'TAC which is exceptional stuff, but very expensive. It would be totally out of the question to paint a plane with it. The most economical water base would likely be Wicked or Auto Air. I shoot E'TAC in an ultra high dollar Iwata airbrush (over 500 bucks) that you put in just drops of paint.