I have the same wobble when heavily loaded. (two side cases, bicycle, tent and sleeping bag on top of the side bags). I make sure my air pressure in the rear is 41 and put the front up to 36. The wobble disappears. With lower air pressures, when the bike is only carrying me or a lighter load, the wobble is not there. (Continental Trail Attacks).
Make sure your air gauge is accurate also. The expensive, dial-type one I bought was reading 7 pounds under and it took me a while to catch on as I trusted the thing due to it's cost.
Maybe this will work for you or help.