We have "double-towed" since we got our first FW, 1993. Here is a picture of our package getting ready to go up to Jackson Lake in Grand Teton National Park. If it works. Just copy and paste and it should come up just fine.
2012 GMC 2500HD D/A Crewcab
2012 Jayco Eagle SuperLite HT 26.5 RLS
2009 Crestliner Superhawk 1900
2013 Polaris Sportsman 550 EXP
2008 Polaris Sportsman 700 X2