what at least some of us (well at least I) do is have three regular 110 volt outlets like this one:
one that is wired direct to the generator, one for shore power, and another that runs off of your inverter. The inverter is a gizmo that changes 12 volt dc (bus voltage) to 110 volts ac (standard house voltage)
Then the entire bus (assuming no a/c) can in most cases run off of one circuit. Power for this circuit comes from a standard 110 volt plug, like this:
This system keeps things simple, and makes it impossible to accidentally connect the geni to shore power which would be disastrous.
You can select from inverter, shore, or geni power by simply choosing which outlet to plug your bus power cord into.
Remembering to keep safety third, you probably want at a minimum to have a gfci outlet that the main power runs through....and having a regular circuit breaker isn't a bad idea either. However.....i'll prob be hung for this next statement....not having a gfi or a circuit breaker is probably ok. Having a couple outlets running your tv, a light or two, etc inside your bus without the above safety devices isn't really any different than plugging your tv and related items into an x-tention cord. I have a lot of water in my bus, so i opt for the $20 gfi.
there are certianly a lot more complicated and expensive setups, but this is simple and cheap. A 110 volt outlet at home depot costs about 50 cents.