Weapon Training (Ex): Starting at 5th level, a fighter can select one group of weapons, as noted below. WHENEVER he attacks with a weapon from this group, he gains a +1 bonus on attack and damage rolls.
Since you are playing a home game ask your DM if you could swap spells for a (diminished) sneak attack progression. That way you keep your performances, but stay 'mundane'.
Go straight Bard. It gives a lot of skill and "face" potential while allowing you to keep up in combat with buff spells and bonuses. Use a crossbow to get around your low Str, you won't be the star of combat, but you will be a valued ally. Also don't play with people who stat dump.
4 Winds Fantasy Gaming has a 3rd party supplement concerning the loss of a body part for Pathfinder, Strategists and Tacticians. That might point you in the right direction. I have considered homebrewing some rules based on the Blood Bowl casualty chart after a character falls below 0 HP. I like the idea of more dangerous combat. I hope it works well for you and the others.
Why don't you take the DR for a creature multiply that by 5 (or a factor that seems appropriate) then add that in HP and remove the DR. In this way the creature maintains (nearly) the "correct" toughness and your players feel like they are accomplishing something.