The travel trailer I tow is only 3500lbs fully loaded, but once I add my dirtbike in the bed, fuel, tools, extra parts, extra water, fire wood and a few people I am pretty close, if not over, my payload limit for a common desert trip. So air bags are most definitely for payload rather than trailer weight.
I didn't realize that the active suspension was so hard to adjust. It looks like I went the right way going with air bags. I have a bicycle pump behind the back seat that I can use to pump up the bags (small volume so very easy) and I have the air chucks inside the rear side compartment so they are protected. It is very easy to adjust the height and an ideal set up for anyone that hauls (especially those of use who are leveled).