I think you have a typo here, eth1 is WAN not WLAN

Corrected!

When the VM goes down you can still configure the network manually on your PC and access proxmox directly

Yes, that’s why having this MGMT port is so important. Time to make some more cables :P

This is why the hardcoded ip will still work.

For some of the critical infra, I will probably hardcode the IP

I saw that you added the detail that you’re also running another vm - AFAIR you could route that via the management port as well with via proxmox without added complexity.

I’ve elaborated upon this in this comment in this thread. Please check and let me know your opinions.