I love my Tundra, it does great. I did add a lift, and airbags to get the ride i wanted. E rated tires are mandatory for any load beyond a day at the beach.
From what i have seen, all trucks either run STIFF rear springs or airbags to carry any load- be it a F550 or a Toyota. I carried my camper on a couple trips w/o anything to aid, the springs had a 1/2" from the bumps. You will probably have to add something to your truck to help carry a heavy load especially if you are traveling off the highways- no matter what vehicle you choose, but definitely with Toyota.
Do some research, there is a big difference between the 1st and 2nd gen Tundras.
Again, love my truck. Big complaint is the lack of distance i am able to travel without stopping at the station for a fill- 26gal tank is silly.