I didn't bother with emulating CP/M itself, just the Z80 CPU+RAM and disk interface, which I made compatible with Udo Munk's z80pack. I was able to use the stock z80pack BIOS/BDOS so I didn't have any issue getting it to run.
Yeah I'm doing things the hard way, for sure! But the project grew little by little, and I'm enjoying the process.
(And it has to be said one of the reasons I'm interested is because I have a Z80-based single-board computer which runs CP/M natively which helps for testing things.)
You are going deep!