I thought there might be something worth reading here, but I stopped treading the extended original post by around line three. The issue isn't that important to justify the ink/bytes/pixels/bandwidth needed to slog through it.

Overhead space is a "shared"resource for all ;passengers. Figure out a way to share it with your fellow travelers who are in the same boat as you are. If you want to act like a self-entitled jerk, remember you're not putting one over on the airline. You're only bringing discomfort onto others in exchange for YOUR convenience. If you don't mind being that person, then go ahead. The crew is going to have a place for their baqs regardless. They really couldn't care whose bag goes where. They secretly just laugh at the "I was here first", or "my bag is bigger," or "I have a superior status" arguments that children tend to use on the playground.