I work at a very high volume tire shop, 3-500 units/monthly. Run flats, low pros, you name it we do it.
When you break the bead with the shovel, the tire will pop back onto the rim, but its not seated, what you want is for it be moved by the shovel and then your good to go.
Once the bead is broke and say on the front of the tire its popped back up on 75% of the rim, spin it and place the duckhead on the 25% part thats the bead is pushed down on, then rotate the tire around, using the duckhead to push the bead down a bit. Once thats down insert the bar into the duckhead and try and lift, I can almost guarntee it wont want to come up, keep applying pressure then apply DOWNWARD pressure on the opposite side of the duckhead and then you will see the tire roll up over the duckhead for dismount.
Once the top bead is off, because of the stiffness of the tire and the lift from the duckhead it will pop it off the lower part of the rim 95% of the time.
Hope that helps, I can maybe make a video if needed for more explanation.
2.5yrs of doing this never needed ANYTHING like posted in this thread.