I was looking for a way to add stealth as a class skill to this build, and came across Divine Tracker archetype for Ranger. This lets you get improved unarmed strike for free if you take Irori as your deity as well as favored enemy/track and some additional class skills.
You lose 1 CMD from the second rank of Weapon Guard, but the bonus feat is made up for with the Divine Tracker bit.
I think you also end up with higher saves, but to be honest I am not sure how that is calculated.