My boat has an adequate box under the companionway that holds the original distribution panel, fuses and switches. It's all behind a door which works fine. In my case, I have to add some circuits so rather than start with a new panel, I'll add a second set of fuses behind the switched/fused distribution panel, but won't need switches. These additional circuits will be for switched appliances like VHF, GPS, plug in receptacle, etc.

Breakers are great but fuses still do the same thing protecting wire in case of an overload. I don't replace many fuses anyway.