I've had really good luck using a sheepskin mitt -- which is NEVER used on wheels/tires, I might add. For the high spots I just put the pitt over a paint pole. Like everyone else has said, use a LOT of water, but aluminum is soft and I think mild scratches are probably an inevitable consequence of owning an Airstream.
"SilverLeaf II" 2015 30' Classic
2014 RAM 2500 Laramie 4x4 CC w/6.7L Cummins
WBCCI # 3430-Unit 21