xtruckerbob, I take a little exception to your remark. I have towed double since 1993 and have yet to see a wreck involving a fifth-wheel pulling another trailer. I happen to believe that most of us towing double are overly cautious and take very few chances and, therefore, have very few accidents. You are right about not being able to see the second trailer, but if you do see it, you are probably going to have an accident due to sway, or you are going around a corner and can see it in the inside mirror surface. I know my experience is probably not as vast as yours, just thought I would share my ideas with you.
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