You can use FDE and setup a minimal ssh server like dropbear to run at startup. This way, you can supply the password via a keyboard connected to the machine OR via ssh. This gives you a similar workflow to the data partition you mentioned, but encrypts the entire system.

I hate the cloudflare stuff making me do captchas or outright denying me with a burning passion. My fault for committing the heinous crime of using a VPN!