Have you ever considered a defensive position? A plan for what may happen? This would be my first consideration.
For example, where I live the only way into the bedroom is down a four foot hallway. I have a heavy wooden hope chest placed at the foot of the bed. Anyone trying to enter will find me behind the chest in the dark. They will be coming down a dark hall,into a dark room with a light behind them. Would make for some fun silolte (sp) shootin.
Once you have your emergency plan, then devise ways to fit your shotgun into it.