I just went to the Ram and F-150 forums and did a subject search for "bounce". I would post links, but I don't know if that's allowed here. Anyway, they have the VERY SAME complaints going on there too about the California freeways and the trucks bouncing around. This does not appear to be a Tundra only issue. I don't think Toyota should take the fall for the crappy roads in California.
I just got back from a trip that took be over some less than perfect terrain and I had my driver side mirror tilted in so I could see the bed. There was NO excessive bouncing at all. I have the TRD suspension and a 125 pound fiberglass
tonneau cover on my truck.