jeebus @ mmw
+1y
When ever i set something up to tow, this is my go to setup.
Parallel 4link, with a watts link. Bag over axle, or just behind or ahead of the axle.
Ive seen many horror stories of people doing bag on bar, then towing something and watch their bars bend with the extra weight.
Another thing to look into if you are concerned with the lift and ride quality of bar on axle, add a second set of bags on the bars, so that when you are riding with an unloaded truck, you can use the bags on bars, then when you have a load to haul with the truck, inflate the bags over axle, and you have the towing capacity.
Taylor