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

Way too much. First, you will be over payload. You're payload rating is less than 1500 lbs. I have a '12 Tundra with the same set up and tow a 5,943lb dry weight (yellow sticker) trailer that is 31' 11" long from hitch to bumper. There is no way I would tow anything heavier or longer, and I don't think that I could legally. You need to be looking for "real" dry weights under 6,000 lbs.