I think the best thing to do for your battery health is to trailer the boat down to the Carolina sounds and go on a sail with me. A nice sunny 50 degree winter sail will top them off nicely!
I copied Steve (thanks Steve!) and put a compass where he did. It's a good location. I like that it's on the centerline of the boat, and it's easy to get power to it for the light.
Looking forward to following the race; thanks for the reminder. My favorite B&B design is the EC-22; so I'm rooting for that boat. Is this their first time in the EC?