We have the entire cargo area lined with dynamat (including wheel arches) before having a full, 2.5 inch KPM system fitted. Don know if it drones as I dont know what a drone sounds like. Our AFM is still working and we use the semi auto function a lot. Isnt your Cruise For Charity 8 event coming up soon. Oh wait that is Brisbane. Go to the one in Melbourne and ask the question there where you can compare with other wagon owners. Hope you find a quick, cheap and permanent fix.
ON a side note, I'm off to Paris on Sunday for the third leg of our European tour and I have hired a maloo ute for a day for a trip from Bern to Brussels. Cant wait to wind up that V8 on their open roads.