Space is usually a scarcity onboard a boat, and It's a very fulfilling feeling to be able to utilize the space just perfectly - though, long time since I've had that feeling personally.
I think last time I had it was with my previous sail boat when I replaced the battery pack. I had one starter battery in one storage room and one consumer battery in another storage room. One problem was that I stored tools and many other metallic things there (like the handle for starting the engine by hand-cranking), I was always worried of an accidental short-circuit. When refitting I managed to find batteries fitting perfectly - and after the refit I had the smaller and less accessible room completely filled up by two consumer batteries and one smaller starting battery, while the other room could be used for safe storage of tools and equipment.
I have 3 batteries, 1 starter and 2 service. But they are in the same compartment and seperated from everything else.
I've seen some accidents with exploding lead acid batteries, so I'm kinda paranoid about safety. There are also many fuses close to the batteries to minimize the danger of a cable-fire. And never put anything metallic in there - a good battery can deliver 500+A ;)
Here is an example of a ship battery, which did explode:
The owner was lucky: He still has his eyesight, only slight chemical burns of the lungs and he had to throw up because of the fumes from the sulfuric acid ...