Don't know about 'reining in horses' but I do believe in following the flight manual.
In four years of flying the MD80 I never had a directional 'issue' like this one but we never used that much reverse, especially on a contaminated runway.
When you start talking about manipulating reverse to straighten out an aircraft that's starting to go sideways you're kidding yourself.
The reason you're having this problem is because of rudder blanking, this is what you need to eliminate immediately.
That's why the manufacturer recommends reducing reverse immediately and that's what you should do.