Yep, still hanging around waiting for spring
They
shouldn't interfere with the WD aspect of the hitch. However, they will change the amount of weight being transferred. The weight distribution is done by utilizing the hitch head as a fulcrum point and levering (with the arms/bars) the hitch into the air, raising the rear and moving that weight to the front end. The distribution is done with that levering of the rear frame up by the bars. Once the air bags are on and the vehicle leveled, the WD system can be adjusted; but...the amount of distribution will affected by where you travel. Read on...
I, personally, don't like the air bags. They tend to alter the ride of the vehicle, both loaded and unloaded, usually making it worse; they require constant adjustments to keep them aired properly (you'll need a lot less air as you go up in the mountains than you will at sea level). More when it is cold, less when it is hot. They tend to develop leaks at times that are not convenient and unless you travel with a compressor, you'll be pulling into and out of service stations to air them up. I won't go into their longevity...
If you need support (doubtful), or stability aids (again, doubtful with a bumper pull), I would recommend something like the Timbren SES system. No air, no bags, no adjustments, no maintenance; they kick in when needed and don't affect the stock suspension when not needed. A lot of us hauling 5vers (much more affect on the rear suspension than a bumper pull :shock: ) use them to aid in roll suppression. When I'm not hooked up to the 5ver, they don't even touch the axle. When I've dropped that 2000 lbs into the bed of the truck, they don't so much support anything as they brace the truck against roll (lean) and sudden pot-hole bottoming out.
That's my dissertation on air bags...they have their purposes, but, for towing, IMHO, are not necessary and can actually be detrimental in a
stable weight distribution setup in traveling since any change in altitude will affect the lift that the bags exert and that in turn
will affect the effectiveness of the weight distribution by changing the "stock height of the hitch"; remember that height is the fulcrum point and raising or lowering that point changes the amount of weight being destributed. The affect on weight distribution is real, but, will be minimal unless traveling in the Rockies. Still, more bother than they are worth and there are better devices to use that won't have an affect on the weight distribution setup and function nor will they affect the factory ride of the suspension.