Is all up weight of 9500 lbs. too much for Tundra 5.7L?

I agree with the others. I think you're asking way too much of that truck. I also think you're underestimating the loaded weight of that trailer. For reference, mine lists at 5800# dry, but weighs in at the scales at about 7500#. I wouldn't want to go much bigger or heavier with a 1/2 ton. I'm guessing yours will be 10,000#+ when loaded. That's firmly in 3/4 ton territory.

-- Rob