Mopar44: Ha Ha....I was just thinking about that exact same thing while taking my evening walk before. I was visualizing how the truck would look with the narrowed cap and the storage boxes sticking out. I also thought about how small the capacity would be making the cap kind of a waste unless you carried some kind of tall item that needed security or weather protection.
I don't think a cap can be fitted to the cargo box since the Ram storage lids impinge on the cargo box space when they open.
I have had a number of caps on various pick ups. I seem to always find that what I needed had somehow migrated to the very front of the box. This required me to crawl on hands and knees inside the cap to retrieve the tool I needed. No thanks. Never again with a conventional cap. I have seen really neat caps that have raised roof lines man sized rear center door to walk in and retrieve whatever you need. That is the only cap style I could ever see using. Only the young guys in their 20's can crawl around on their knees with the standard caps. But it is a moot subject with the Ram Box equipped trucks.
Photo below has BackFlip 26207RB tri fold cover folded up as far as it will go.