Should do an angle check with the head rotation to make sure we're really behind the back. Probably a 120 degree check instead of 180 like the vanilla shield.

It also looks like the bag hitbox is way in front of us while flying forwards. Not sure why, but this would explain a lot.

Re-opening, as we should add an option to make the bag openable from the back or shoulder, back only, or shoulder only

Interact keybind support here could also work and may be a good idea (since left click is out of the picture)

I think I'm going to be moving the "back or shoulder" option to be in the future, mainly after I get some feedback on the 1.4.0 implementation of the bag.