You may be overlooking something - with the transfer case in neutral, nothing is moving in the transmission which the manual says to put in PARK, not neutral. The only things moving are the axles and driveshafts, and the transfer case output shafts. To the best of my knowledge, transfer cases do not use pressure lubrication and the "splash" lube should be sufficient for the output shaft bearings.

I maintain my opinion that dinghy towing that Yukon as a "toad" is fine, if you spend the big bucks to set it up correctly. If it wasn't fine, why would the owner's manual give you the detailed procedure for doing it - and have no mention whatsoever on distance or speed restrictions? The manual also doesn't say anything about the need to start the engine at fuel stops.