I have a 2000 Tundra, V6, 2wd. In many ways I love it. I go a lot of intersting places in just 2wd.
Look closely at what goes into that payload. You put LT 245 75 R16 tires on it and that uses up payload. Then you count yourself and all of your passengers, plus all of your gear. You don't have room for that much camper.
Look at the pop ups, Outfitter, FourWheel, NorthStar. The largest hard side camper which I know of having been put on a Tundra is the SixPac, which is made by the same people who make FourWheel. I considered the SixPac. The company is very good on e-mail contacts.