Welcome to the Transformer Club! I'm with you about not tearing the van apart and having it unusable and expensive, all at once. I don't haul a motorcycle, but just about everything else and want to have quick access to that space whenever I need it. This is my open setup now:
I'm looking at building a platform bed, probably on narrow, tall, boxes, something along these lines, to preserve the middle space:
As to a rear fan, I really like what this guy did. They used plexiglass:
The interior build isn't the prettiest job, but I'm impressed with how he fabbed up his van, quickly, and with basically no experience. The thing that really caught my eye was how he "modularized" the sections onto floor pieces that bolted into the original seat holes, which makes them removable. Then he added flooring.
You can take a look at his site here:
Cross-Country Travel Adventure & USA Tour - My Big Adventure™
Good luck with your build. I'll be following.