I agree on the topic of mouse pads - What they're supposed to do is stop you from bending your wrist, but like you said, you end up with pressure on the very part you're trying to avoid.

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.