Yes, there was a Tornado (F2 I think) put on a pole at Farnborough (again I think) with lights on along its leading edges - these lights would match the background brightness and so reduce the contrast of the aircraft shape. I remember seeing a video of the trial on an EW course many years ago. Head on you couldn’t see it from a mile away - pretty impressive, but very expensive to maintain (this is before the day of LED lighting that lasts for many years and is more robust). I guess Adaptiv has taken it to the next level - robust, light and also provides an IR capability.
There was the trial with a Harrier ( GR5/7/9?) with lights inside the intakes - turn them on and it disappeared. Impressive with that frontal profile.
On more recent trials with tanks....
https://www.dailymail.co.uk/news/art...amouflage.html