A Fair bit - Depending on what sort of Mech you are adding to your trav universe, pick any answer you like.
Alternatively, for "small" mechs - use battledress - your all arround handy dandy fightin' suit.
If someone built a "big" set of battledress using force feedback etc, Build it as a vehicle.
Keep in mind that weapons will do much much much more damage than fists - the only reason a mech might use a fist would be for damage limitation.
