I am not in the construction stage yet. Instead I am doing a lot of reading and planning. I want the flexibility of both 12 v and shore power. But I want to keep the cost of construction as low as possible.
For me this means I have decided I don't want to pay to install two separate electirical lighting system.
I will install only 12 v DC lights, fans, etc. I am planning on using some LED lights as well as a few select incadecent light and a 12 v DC area florecent in the hatch pantry.
This will enable me to use the conveniences I desire when on deep cycle battery supply. But I am also designing a converter that will power the 12 system when there is AC shore power.
My system will include all the saftey features of a 12 v DC fuse boxe, as well as a pannel to control the system. I will use a double pole double toggle switch rated at the required amps to switch between battery and the power supply converter.
The power supply is will use is a modified computer power supply adapted for 12v DC. You can see these components at the following sites.
When shore power is available, I can use a heavy duty outdoor extension cord and a power strip to power AC needs
Read up, plan the work and work the plan!