So after some lengthy testing of the various trans positions this afternoon (park, neutral), and then attempting to fully turn off the power with the car while shifted into neutral, there seems to be an in-between state where the "Accessory Mode" is off but the dash continues to display "Shift into Park".
In this interim "Shift into Park" state, the center panel is semi-lighted and no other dash panel is active (navigation panel is off and dark). In this state with the car in "neutral" shift position, the steering is free and unlocked.
After an hour or more in this state, it appears that there is no way to fully turn off the "Shift into Neutral" warning with the trans in neutral. But the steering continues to be free and unlocked while the warning is visible.
So it appears there must be a reduced power position and does not require the vehicle to be in the full "Accessory Mode", which obviously has more features active and power drain (radio, other lights, etc.).
Hence, I believe the Owner's Manual is correct and with the vehicle in neutral, the steering stays unlocked but required the warning light mode. I would assume one benefit of this interim state is it has much less drain on the batteries while towing (although I hooked up a fused charge line when plugged in to the coach).
I will keep doing some tests and keep the fingers crossed as we set out. And I'll report back on the findings.
Thanks for the response, lllkrob!
2007 Monaco Dynasty
44'; ISL 400; SFT
Towing a 2013 Lincoln MKT