Always love the wiring discussions and have talked to many sparkles myself about my build.
It might take a little physical effort like using plug in types to change around?
I wasn't thinking as cheap as possible I was thinking if the bus didn't start then it was a problem with the bus, if the 12v lights or whatever didn't work then it was a problem with the 12v system and if the 120 house power didn't work then it is within in power to the house (shore/generator)?
I do not want the house 12 or 120 no matter the amps to drain my starting up and moving my mobile house home to diagnose the problem. If my 12 don't work then I look at the batteries and charger or the 12v fuse panel I made and if the 120 panel don't work at the same time as the 12 charger then I know it is external and if one goes and not the other then it is internal to a specific system and not both and if I can't figure out the stuff I built then I can start up and go to wherever I feel I need to fix or better diagnose?
It is cheaper in the long run to keep everything seperate and use plug in plug's and actually know what is plugged in and what is not instead of trying to find/diagnose/hunt down/figure out which switch,charger,relay,converter,inverter,panel board with a bad rocker switch, wiring connection,disconnection? Ain't for me
Keep it seperate and don't over engineer it or (in my opinion ) you will be cursing later.
Cheap engineering means you have to do more than plug it in and walk away? But we are only talking about 3-4 seperate plugs that needs to fit the proper plug in and please don't try to make a (correct me if i am wrong) 30-amp twist lock fit in a 50-amp twist! It does not take much and everything is fried when you do unless your breaker panel is oversized and then your 120 is fried. The old converter/inverter is probably the good but put it where you can get to it and leave space for an up grade?
My build is the KISS method and of course electrical and painting are not my strong points? I know a lot more elect. Than I do paint. One thing I have done right is my wife and will never ask me to paint anything again. I get the primer and sandpaper but I can't do anything for finish