Mixing Vallejo and Tamiya (+ lacquer thinner)

That would certainly do the trick, but I'm trying to do it without another trip to the shop. I prefer not using rattle cans, but the right product for this is probably out there.

Right now, I'm just trying to do it with the products at hand. Even if it all fails, I'll still have learned something about paint :-)

I do feel with simple white paint with gloss varnish, staying within the Vallejo brand should work, but somehow it keeps failing.

Thanks anyway, and that is one nice-looking airliner, by the way!

I second Chuck's idea. I'm a fan of the rattle can for car body paint.

You don't really need to mix anything.  Tamiya makes a color called "Pure White" as a synthetic  laquer in a rattle can.  I recently did an airliner with this, and it looks great, shiny, glossy, smooth and snow white.

I used Tamiya Fine white primer, also from a spray can, underneath it.