> I did eventually get around to using dyn Write, but that still gave me headaches because of how I cannot use impl Write as a result type in closures,

I hope we manage to fix that! We're working on making `impl Trait` usable everywhere a type works. I'll check where "return type of a closure" is on the `impl Trait` radar.

https://rust-lang.zulipchat.com/#narrow/channel/213817-t-lan...

> which I need to do if I want to use tracing_subscriber::fmt::with_writer() and pass in these trait objects.

Would https://docs.rs/tracing-subscriber/0.3.19/tracing_subscriber... help you?

> Thank you so much for taking the time to write this. Means a lot!

Thank you as well for taking the time to fill in more details!