Those sleeping positions are so funny! lol
My cats don't sleep that way; but we never have cardboard boxes around, but I'll try that one day Doe's Prince or Princess sleep like that in boxes or anywhere else?
One of the strays slept inside a closet drawer I put for her under the bushes with a cushion on it, all stuff I found in the street here, until the municipality had a deep cleaning spree when I was in the US and took it all away. She was a happy soul while it lasted.
I once saw one of my strays inside a tupperware cheese box that someone had left around. That would've been a great photo. Only her 4 legs fit in, the rest of the body over the box. I felt so sorry for the poor thing I brought her a big, comfy cardboard box. She snuffed the box and went back to her lovely tupperware. Cats especially love boxes that they don't fit into.