Anonymous Local C&C Server

I wasa playing with backdoors and I was wondering if there is a way to make anonymous my C&C server in order to avoid the target can trace me.
At the moment, Kali runs into a VM with ngrok to expose my server on internet. Moreover I use Windscribe VPN in my windows host machine.
This configuration works correctly and I can connect to my server, however I was wondering if ngrok serveris able, somehow, to trace my real public IP or it just detects the VPN IP.
Do you think am I anonymous enough?

Thank you in advance!

PS: I know the existence of tor hidden service which are supposed to anonymise my server, however the target should has tor installed and I assume it hasn't.