I think you have it backwards. Ergonomic mouse-pads have a big silicone pillow to rest your wrist on while you move your mouse with fingers only. Switching to such a mouse-pad is how my wife got rid of CTS.
I line up the armrest of my chair with the top of the desk so they're a level surface. I adjust the height of my chair so my arm is at a 90 degree angle. My arm runs flat across the arm rest and the desk, and my palm sits on the flat mouse pad. Then, I just move my finger tips to flick the mouse 1cm in any direction for getting to different sides of the screen.
For keyboards it's similar. I use a thin and flat keyboard. This way my elbow (on the armrest), forearm, palm, and finger tips are all in a straight line. If I add any type of wrist rest, then the weight all goes to the wrist instead of being distributed.
Lastly, I dislike keyboards and laptops that raise the backside because they raise my finger tips and put pressure on my wrist. It feels much more natural for the fingers to be lower or equal to the wrist and palm.
Anyway, just my experience. I had some discomfort for a few years, and then nothing for the past decade.
Did you ever get a chance to try a vertical ergonomic mouse? They take a while to get used to, but the idea is that you don't rotate your wrist (i.e your ulna and radius remain parallel) and keep it in a more neutral orientation.
Theoretically the best wrist “rest” in this scenario would be a bed of sharp nails..