This is kind of insanely vulnerable, but I’m hoping it’ll help some people. I made this a couple months ago. I screwed up the day after I made it but I have now been clean for 21 days. I feel hopeful and healthy. I hope you can feel the same. 
To listen while using other apps, switch the player to Picture-in-Picture (PiP) during playback — it keeps playing in a small floating window (the screen stays on).
To listen with the screen fully off, in-browser playback stops by YouTube's design. Open the video in the YouTube app to keep listening where background playback is supported (e.g. with YouTube Premium).
Open in YouTube app