The dinghy towing stipulation is for NICE-Off (Engine Off) coasting. With an automatic you can shift from drive to neutral no problem. Shifting from neutral to drive should be done by rev matching - blipping the throttle so your RPMs are approximately what they would be if you were in drive, then shifting to drive.
Notes:
- If there is a big clunk or jerk, don't use that method anymore. (Some older transmissions pick the wrong gear to re-engage in)
- N to D will cause wear on your transmission, however it is generally considered to be minimal, and worth the tiny bit of wear.
- Don't push in the shift lock, you should be able to shift between N and D without pushing it, this will keep you from shifting into Park or Reverse by accident.
Kirk