I have the same Jayco trailer as coldfusion, 2014 model, at 4700lbs and an advertised dry hitch weight of 485. I also tow it with a Crewmax Tundra 5.7, and have a good WDH (Equalizer). I calculated I'm roughly 100lbs short of my payload.
Anyway the combination has been great...just got back from a 6000 mile trip including Grand Canyon and crossing the continental divide in two different places, one being in RMNP, no problem. The road into Sedona is crazy steep and twisty, no problem in or out. Just drove it smart and chose the right gears and never once got nervous. As a family we do pack light, and never come close to the GVWR, and I do put the heavier things in the rear storage to help minimize tongue weight. The kids love the rear bunks, they're huge. Each can hold 2 kids.
I should tell you I did a lot of research to find a TT, with the same Tundra payload concerns as your buddy. The Jayflight is gonna be tough to beat in terms of overall weight and hitch weight in that floorplan...I could not find one. Its b/c there's no bumpout, which makes it rare. Again, I'm only within 100lbs, so with that truck I wouldn't go much heavier.
2014 Jayco Jayflight 264 BH
2009 Tundra 5.7 Crewmax w/ Tow Package