"I know the shore power connection goes on the left side of the bus for campground hookups" I wouldn't worry much about where the shore power hook up is. While it is often on the driver's side that isn't always true as you will see in the pic from Lake Mead, Az. I looked at the real estate I had to work with in my bus and built accordingly. Having been gifted free holding tanks it became apparent that the fresh water would enter on the left and the black/grey water would exit on the right.. By adding a mascerator to the black/grey tank it became no problem AND no stinky slinky! My propane and CTV happen to be on the left.
Really the only important thing is to locate your house batteries and your inverter as close together as possible to avoid line loss. Mine are about 6" apart. As to inside or outside for the batteries, as long as it isn't going to be freezing cold where you camp, outside is best (you can use heat tape below the batteries to make up for it, however).
All the controls for your electric should be accessible from the inside.