I found this van build to be a different than your normal van build. I will use a couple of ideas that they did.
https://youtu.be/GKw3_nrjL9U?si=clOlrQ7Zbpf-rtrN
A lot of innovation especially utilizing 3D printing. 3D in plastic is a great technology if already made components are available like latches or vents are not available.
Showering could require some ingenuity to prevent water on the floor but double functionality shower and flat workspace is a good idea. Safari Condo has one but with full height walls/curtain.
They did great job to tune their camper van to their needs.