The SAE towing standard does not adequately address RV towing for half tons IMO. It is primarily an acceleration/power/gearing limited test. How much weight can it tow while accelerating to XX speed in under YY seconds. How many people ever use WOT? I do, but I know I am in the minority. Most people never see north of 4000rpm in a gas engine. How well the TV holds speeds up hills after using much of it's power just to maintain 65mph? How does it handle a 10k RV with 1400 pounds of TW?
The Tundra is a good truck. The engine/trans/gearing are strong, near the top in the half ton class. But it suffers from having less than average payload.