I've never had a problem with an AT car in Park - stick cars I usually use E-brake - towing literally across the Country.
Worked for a guy who would use E-brake & neutral on AT cars, never an issue either.
Never less than 4 proper ratcheting tie-downs, crossed left/right at both ends - TIGHT, and checked from time to time - plus the winch cable.
Nothing's moved yet (in many thousands of miles), and some of those cars were worth more than my home (as in Pebble Beach Concours).
Main thing is the car doesn't move back or forth, or for that matter side to side, hence the crossed tie-downs.
Whether I'm towing locally or across the US, same tie-down method, as I've had to avoid some real idiocy and/or junk road surfaces.
Best tie-downs in the world are Mac's, though I've used arguably lesser ones.