I used to use 2 group 27 deep cycle batteries, and I would isolate one of the batteries during overnight stays so I always had juice to start the engine.
This year, I upgraded to 2) 215 ah 6-volt GC batteries in series.
I don’t yet have an engine start battery set up, but I did install one of these Renogy battery monitors..
Very comforting to see ins and outs to the battery bank and have the monitor calculate remaining capacity and hours of use.
i do hope to add a dedicated start battery to the system next year, but this has worked great for my normal day sailing and an occasional 2-night sailing weekend on the hook.
i did turn my fridge off (put a frozen Gallon jug of water in the fridge and a few frozen water bottles in the freezer to keep things cold…
Greg