I doubt that you'll be 'sticking out' in your bum.
Doc will make a pretty secure little 'pocket' for the battery to sit in. The only way it 'mmmmight' end up sticking out a bit is if you happen to lose quite a bit of weight back there....there won't be as much of the 'fatty/meaty' stuff back there and it'll seem as tho your battery has come up toward the surface. From what I've seen of you in the video clips you've shared, you are rather slender as it is, so you probably won't have to worry about this.
My battery is same as Jackie's - left buttock/hip below the belt line.
I'm used to it by now and don't even know it's there, except if I maneuver certain ways in a chair, I might feel it. I can feel it when I put my hand there and press on it, which was a bit 'creepy' to me at first, but I'm used to it by now.