Thank you for your post.
I am working with an empty shell and will overhaul the whole interior including brand new wiring.
You are bringing up very good points, regarding the proximity of the batteries, converter and the 12V
Those combined panels I am looking at are prewired and have house-style curcuit breakers in them. Therefore I am less concerned about the two different systems energizing each other as long as the wiring is solid.
My major concern is the grounding of each system. Like you said I would ground the 12V at disribution from the panel to the shell. The ground from the AC system would also come out of the same panel, but to the main frame.
However, this means having both grounding points within a of few feet of each other. Therefore I was wondering if that could be a potential hazard.