I've got to be honest, I thought the Harnmaster wound system was brilliant and elegant. It was great that a wound affected movement speed, the ability to dodge, and the ability to concentrate on casting a spell. Minor wounds went away quickly, and serious wounds were the cause of concern.
I also found as a Harnmaster GM, it was easy to run too.
It would be possible to do a similar wound system in D&D. The heart of it was a hit location chart, and cross-referenced by the type of weapon (blunt, slashing, and edge).
A possible problem is that Harnmaster uses weapons to reduce damage, where D&D doesn't.
Instead of hit points, for every 5 hit point wound, -1 to hit or any physical skill.
Every 10 hit point wound reduces movement by -5 ft.
Hits to a leg or hip require a variable Reflex save to avoid falling down.
Hits to an arm require a variable Reflex save to avoid dropping a weapon.
Light hits to the torso require a Fortitude save to avoid being stunned.
Heavy hits to the torso or head require a Fortitude save to avoid unconsciousness.
Brutal hits require a Fortitude save to avoid death.
Bleeding wounds inflict 1 point of damage per round - enough bloodloss causes unconcsciousness.
That sort of thing. Instead of a percentile system, a D20 based system requires increments of 5 causing a -1 penalty rather than a 1 to 1 effect.
Healing every night would require a Fort save to reduce each wound by 1 point.
With some work, and playtesting, it could be done.