Full disclosure. I was once involved with a corporate 727-200ADV and one of the owners sons was a very accomplished skydiver. We had plans to make a similar drop down in Florida. During our prep time we watched the US Army jump from an ATA 727 down at Marana, Arizona and watched a video of the US Army jumping from the stairs of a Pan Am B727. The Pan Am video was quite well done from both outside and inside the airplane. Very interesting and very doable for the right person. 4 people on the stair and it would stay fairly well extended. With just one person the opening got smaller but not so small you could not get out without killing yourself.
We never did the jumps as there was a scheduling conflict with airplane and the completion center down in Orlando, FL.