I just pin my PlayerImage sprite/animations to my Player sprite at the start of the layout as advised in the platformer beginner tutorial/s, that seems to work fine and doesn't need updating each tick.
The Player sprite is just a basic rectangle for collision impact purposes. You should be able to pin hands to your torso in the same manner though whether you've used a basic rectangle as your Player or gone with one with it's own animations etc.
Edit: I've re-read your post, sounds like the reasoning for your question is that you just want to keep a standard sized bounding box/collision shape? Using a basic rectangle as the Player as advised would solve this I think without having to pin hands on?