I would add that once you know the degree of prop walk in reverse, you can plan on it. It's always there, and has uses.
What you can't do, in confined spaces, is stop the turning with rudder once "overturning" begins. That's what freaks people out, and makes reverse seem diabolical.
Try this: with the boat stopped, learn to turn it 360 degrees, in place, using bursts of forward and reverse.
In reverse, keep helm centered--let burst of prop walk turn you.
Then shift to forward, and spin the rudder hard over--let burst of forward turn you.
Then center rudder, let prop walk work.
The boat will perform a series of "K-turns", moving forward and backward only a foot or two.
The only thing that brings peace of mind when backing up in tight spaces is knowing you can maneuver just as you want to, and stop any undesired turn or approaching collision.
When practicing this stuff, try big bursts of power. You may be surprised at the predictable effect.
Since there is a lot of turning of the wheel and shift and throttle changes, it takes confidence. It isn't subtle.
But once familiar, it's easy.