I have flat towed mine 1700 miles one way (And BACK) from the mountains of northern Nevada with no problems.
I did follow the owners manual and started it, let it idle with the main transmission in gear and the transfer case in neutral
at the end of every day's travel.
On my rig with stock axles, I have noticed after long on highway runs, my rear axle gets very warm too the touch,
and "Heat Gunned" it at 130-140 degrees. (Note Day Temp was 95 F)
CAPT