I am thinking of modifying my panel by making it into a quadcab... The second mod. would be to
create approx. 4' 6" box with a niece lift cover... A rear access hatch to create a place to sleep or haul things that are longer.
I sounds like you are planning a '53 Avalanche. I love my 2003 Avalanche. I think a '53 version would be a cool truck. I say do it before someone steals your idea.