I don't think you read my post thoroughly. I made a clear case that I'm not worried about Choice Band Tyranitar because nobody uses it anymore, and the other Pokemon I'm more worried about taking down.
Second, my scenario assumes that at around 60% HP I survive another burned Crunch (which will do a maximum of damage of 40%), then use Leech Seed, which will restore me to around 35% because of Tyranitar's huge HP stat. 50 percent chance at Harvest, and if that fails then I have Protect so I can restore more HP with leech seed next turn, and another 50% chance at harvesting sitrus.
And if you're talking about a scenario in which Tyranitar predicts a Protect and switches out, I've already accomplished my goal. Tyranitar is burned and my Trevenant is still alive, and there's a very good chance that my Trevenant has over 50% of its HP left. Furthermore, said Tyranitar can't serve as a viable counter to my Trevenant anymore.
My Trevenant not only cripples Tyranitar, but actually has the power to stay in against him an take him down, which yours has more trouble doing because even a burned Tyranitar is hitting you for over half your total HP. Not to mention my version serves as a much better counter to Shadow Claw Excadrill and literally every physical attacker that yours can't outspeed, because it can actually stay in against them.
So go ahead and use your speed to burn Tyranitar first. I'll take down every version of Tyranitar just as easily or more so, with the extremely rare exception of the Choice Banded set. I'm sure our respective Trevenant suit our respective teams equally well. But before you write it off, try my version and see how well it works for you for a while.