How about a feat to build on Tough? I’m trying to walk the line here between too powerful and not powerful enough.
You are just a mass of muscle, and for anybody to hurt you they have to cut through it all to hit a vital. Increase your maximum hit point total equal to 1/2 your Strength modifier, rounded up, for each level you have. When you gain a level or increase your Strength modifier, increase your maximum hit point total again.