“...around 40 feet in length—plenty of room for two people”
LOLOL...yeah, right.
You need a Bigger Boat!
JAWS.
If she (the vessel) is beamy and she (the companion) isn’t beamy, 40 feet could perhaps be enough... for a while.
Beneteau put out a 57-footer a while back that was quite spacious. I could see that being sufficient as a blue water liveaboard.