For the A-6E in low-vis, I'd say 99%. The A-6 just barely made it into the "resurgence" of allowing ANY high-vis at all. For many years, there was not a single one with even BLACK allowed, much less any yellow/red/white anywhere in any amount.
Here's VF-142's CAG plane during the "grey" era:
http://www.topedge.com/alley/images/f14b/f14b142b.jpg And that's notably "contrasty" for a CAG of that era. (Dark grey along the top of the nose and spine).
Here's a bit more typical one, VF-102's all-grey CAG:
HOME OF M.A.T.S. - The most comprehensive Grumman F-14 Reference Work - by Torsten Anft! But even that is more than the A-6's usually got. (He's got dark grey fin tips and tail lettering)