I had a similar goal for my board. And I am working on a 2nd board where i can swap between the two. I did this with the motor, mast, ESC (and receiver) all connected together permanently (no connectors but I could still unsolder it). ESC is in waterproof box I milled out on the top of the mast. Out of that is my connector that goes to the battery and a wire for external reciever antenna. I have 2 batteries I can swap between now.
Here i am pressure checking it.
Aluminum box works great for passive cooling as well!
Edit: link didn’t appear to work properly. Here are done pictures
