You can stuff things into /etc/rc.local to have them run automatically on reboot. Which means you'll need to use command-line versions of the tools.

I have never used macvlan nor Caddy, but I did find this tutorial on the former:
https://sreeninet.wordpress.com/2016/05/29/macvlan-and-ipvlan/

The Caddy site doesn't seem to have a basic "what is Caddy" explanation, but it appears to just be yet another web server. Apache is the most commonly used web server, fully Open Source, and there are tons of tutorials on how to use it. I run one Apache instance internally, and another for the WAN. Without need for macvlan or similar magic.