Some guy did this, I saw the results at the Kansas City show quite a few years ago, before the stovebolt crew started going. He put them together backwards, rear to rear. So it had suicide doors. Looked ok, but I bet it was a lot of work.
Interestingly, GM actually did make some "quad cabs" back in the early 50s/late 40s. I saw one of those cabs for sale on ebay a long time ago. He did not know what it was used for. But then recently I found one at the air and space museum outside of Tucson. It was used as an airplane tug, so of course it had huge wheels and engine.
