My only question would be....WHY ?
I simply use a 30A-to-20A adapter to plug my rig's 30 amp power cord into a standard 20 amp outlet in my garage.
And if you do go ahead with it, how does "movement of the motorhome" figure into the plan ? If you're plugged into shore power, you aren't driving the rig.
Am I misinterpreting your plan ?