About the unfair boss fight, you could also probably set up an event that spawns the boss one second after you get into the room if you want to keep the door in the middle. Maybe it would also be nice to add an indicator for where the boss will appear when it does if you decide to do this.
Edit: I see you already fixed it, didn't see the edit on your post
I have absolutely no idea what my current project is... My interests always seem to shift
Looking back at every one of my posts, I cringe, hard, very hard.