This is why I said "simulated" yoke walks..
Set up in a cage that has sabre style pins that run from front to back of the cage..
Set those pins so they are maybe one hole under your shoulders, so that when you lift up the bar on your traps, it's barely clearing the pins (obviously you have to put the barbell on the pins before loading it)
Lift it off the pins like you're going to squat, but instead you just march in place... And just like a yoke, if you wobble, you're going to hit the pins (would be the ground with a real yoke), which will cause you to have to balance and stabilize..
I've worked up to a 600lb bar for about 30 nice, steady steps...