This maybe something that many people know. If not I hope this is useful.
When I had the head on my Epson P8000 replaced last year the tech showed me how a blue LED flashlight made it easy to see the yellow nozzle pattern. It works under dim lighting (ie not too effective in full daylight) but made it really easy to see the otherwise rather washed out yellow stripes. I planned to buy a blue LED flashlight but spinning the little colour wheel in my head it occurred to me that red and green leds might be able to enhance the light cyan and magentas. So my initial thought was to find 3 LED flashlights, RGB, one for each colour, but looking around I found one on Amazon that has all 3 colours as well as white. You just cycle through them by partially pressing the back button.
It works pretty well and as I run my nozzle pattern early in the morning the house isn’t too bright and I’m always able to see the patterns enhanced by the colour LED.
I think you get an idea from the attachment although it seems that the camera does a better job than my eyes. The green is clearer (for VLM) than I see for example. I’d say that the green has the weakest effect (on the VLM) but it’s still worth having. Nothing helps with the LLK I’m afraid.
When I started using this LED I had cataracts in both eyes, one being almost useless as the contrast was so low. I’ve had both done now but I still find the LED very effective.