Thanks for all the great answers. Ok. I don't feel so stupid anymore.
All we really need to use in our camper would be whatever is already running off the 12v system, such as lighting, fridge electronics (LP mode), on board water pump, and LP water heater igniter. And hopefully somehow hook in our laptop, which we do have a 12V cigarette lighter located right around the corner in the bedroom. I wonder if its possible to connect an inverter into that to run the laptop and hairdryer? Or would it blow a fuse?
I pulled the plug on shore power to see how well the 12V is working with the existing Exide 24MDP battery. I don't know how long it'll run without the grid. But I could always get another battery and tie it in.
But my biggest question there would be how to connect a solar charge controller to the existing battery while leaving the 12V camper wiring connected for use? Does the controller basically go in between the batteries and the controller? Or does it all just hook together onto the battery?