I think you're on the right track with Wireguard.

I'm also running Jellyfin, but mostly Navidrome for music. I've been pretty satisfied with the latter.

Consuming music outside the house has been a significant issue. I mostly tried to go the offline route: download some music to play while you're out of the house ... and on Android the experience has been overall very poor. My least worst experience was with Substreamer as a client, but still not anywhere near good.

Where I'm at today is with always-on VPN through Wireguard and the experience is significantly better than any other solution I've tried before.

It's been years I haven't played with mpd, so I can't comment on that.

You have to document or share how that's going for you somehow. This is an incredibly interesting subject. I haven't read very much so far about winter sailboat life "out East", mostly from people on the West coast like Vancouver / Seattle area. Other sailors from the North-East I know simply fly out South for the winter.