My current setup is just the one breaker which functions as the main breaker and the one and only branch breaker. Blue Sea only has a single pole 15A breaker. To get dual pole you have to go 30A or higher which won't properly protect a duplex outlet. It looks like there are other RCBO breakers available and some have 2 poles at 16A for residential/industrial use. It doesn't look like using just one breaker for main and distribution is the way the marine industry wants me to do this. Is there a good reason for this?