Yep, I did it....
Hauled some tile the other day. I loaded 40 boxes of 18 inch porcelain tile in the back of my truck. Wasn't sure of how much weight there was, but I know I had a 3 inch drop in suspension!!! Yeah, the tires were pretty much my shock absorbers! So I hauled the load about 15 miles, and it drove pretty well! Still had good acceleration. Of course, I was easy on the pedal though. The truck handled the load quite nicely! I've hauled some heavy tile loads in a 3/4 ton Dodge cargo van, and my old Chevy Silverado ext cab 1/2 ton. I felt alot more secure with the TUNDRA. It really drove well! So tonight I brought a box home and weighed it. Each box is 53.5 lbs. So times 40 boxes equals 2140lbs!!!! Over a ton! And the same day I went back and got another 40 boxes, for a second trip. I still have another 40 to pick up yet. I drove it up a steep inclined driveway without a problem and without 4 WD also. Very impressed with the truck!
Pictures for everyone to see...
Her she is FULLY loaded
Here's the load
Here's the before and after suspension drops
And the rear bumper
And a shot of the bed gap (no change)

Ha, ha sorry for the side view!!!
So, I am not encouraging anyone to go out and overload their trucks, but just wanted to show what they can handle...