I’ve done this, assigning 5 to TC2 and 4 to TC1, with 0-3 on TC0. Since priority 4 still permits significant interruption of priority 5 traffic, I want to try lowering it to priority 3, while moving 3 to TC1, to see whether that will be better behaved.
At the rate I am currently sending, with no competing low-priority lossy traffic, I am getting no drops.