I heard a scheme where the control surfaces of white GRP aircraft would be fitted with a silvered window tint style silver foil that would twinkle with the constant twitching of the controls.
Did anything come of this as it sounds like it had merit.
Also I have a picture of a Viking being winched with dayglo patches. Port side not much use in the bright light but the Starboard side the duller conditions meant that wing was invisible save the patches.
See
http://www.edenbridgeaircadets.com/whatwedo.php?page=6
Getting something to work under all conditions seems difficult