You can get some pretty great headlamps that help with light, around $75 for something with decent quality, battery and bright enough. I typically get most of my running in while the kids are asleep which means very early or late runs. I'm lucky enough to live in a place with well lit running paths all night though so I haven't had much experience with unlit roads. I do trail running with a headlamp sometimes though which works well enough.
For the sun, I'd highly recommend covering up vs sunscreen. A long sleeve lightweight shirt + a bucket hat would go a long way, or those weird running sleeves that people wear.
I don’t have an issue with bleeding nipples myself, but I’ve heard people swear by products like nut butter or body glide. I just use normal Vaseline when I’m having chafing and it does the trick.
If you're going to big/medium-sized acts from musicians that have definitively "made it" then I think this makes sense. I've been to plenty of shows where an encore was neither expected nor desired, and others where an encore came at (what looked like) genuine surprise to the band.
So yeah, when you're selling out all your shows and the last 10 all demanded an encore, then just start baking it into your set, but there has to be some marker of when you've reached this point.