I would still use a dolly with any FWD automatic as you can't completely disconnect the transmission from the drive wheels. Strange why the manual would say the 3.9 is a no go, but it's fine with the other engines. I wouldn't trust flat towing it. Besides, having the front end off the road will wear the rear tires more in line to the front tires as the vehicle is front weight biased so you can cheapen out on your next tire rotation.
'11 Ram SXT 4x4 quad cab - 5.7L V8; 128,200kms
'09 Malibu 2Lt 3.6L - 140,000kms purchased 1 March 2019
'06 Pontiac G6 GT - 3.5L V6; 162,000kms (rear ended 15 Feb 2019, and given totalled title by insurance)