We have a 2003 Pilot, which we do not use for towing the Safari. We did tow a 17', 3500 lb SOB with it. It towed that OK. But note that the 4,500 tow limit on the Pilot (at least the '03 model) was for boats and it was 3,500 for trailers. The difference has to do with aerodynamics, so maybe an Airstream would let you get away with a bit over the 3,500 tow capacity.
By the way, the Pilot got 10 mpg pulling the 3,500 lb SOB. My Mercedes ML 500, a V8, gets 12 mpg pulling our 5,000 lb Safari.