I now know AWD towing should be done with a flatbed type truck. But say you have a sling type truck and towed an AWD with the rear wheels on the grounds. This could maybe cause damage to the front end but the front wheels are free to rotate. If the driver went slow and a short distance would this greatly reduce the risk of drivetrain damage?
The reason you should tow an AWD either all 4 wheels on the ground, or all 4 wheels on a flatbed is because just having two on the ground means the differential is having to carry the, well, difference in rotation speed between the front and rear wheels.
Having the front wheels fixed in position would obviously be bad, but even allowing them to rotate freely will lead to significant speed in your diff, generating heat, and possibly causing failure.
If you were to do this very slowly, and for a very short distance, yes, you'll probably be okay, but I would suggest it isn't worth the risk to find out. The value of your vehicle is significantly more than the cost of a flatbed rental.