I've never had issues with typing. It's the mouse that irritates my wrist. I swap it from side to side to alleviate the problem. i do have wider hands...
Could try a ball mouse, the one I use, has the thumb on the ball, and the normal fingers for the buttons.
I tried one of those, but you can only use them with left or right hand and the wheel still aggravates my wrist. Swapping from left to right seems better. I also add in a little weight training and I don't have any problems.
Did you check finger operated trackballs? They are symetrical and can be operated by both hands.
Examples: Kensington Orbit, Kensington Expert Trackball, GameBall trackball, Logitech TrackMan Marble, X-keys L-Trac.
A split keyboard with a trackball placed in the space between the halves may be worth considering.
I actually swap between a split keyboard and regular keyboard. I find the variation helps.