I’ve got a california king bed and frequently wake up with my feet dangling over one end and my arms over the other. I really, really doubt I’d fit on an 82 inch bed that has no space around it. And that doesn’t get into the constant light and noise and people on a plane which make it even harder for me to sleep, even if I could get comfortable.
Though many people have made it clear to me that airplanes are not supposed to be comfortable or nice, just something to endure to get to where you’re going.