I was passed by a truck carrying a camper with a 2'-2.5' single extension to tow his 16-17' aluminum boat yesterday (his speed is for another topic). I couldn't believe the flex in his connection as he was traveling down the freeway. Just seeing that made me feel much better about my double truss setup.
As has been posted numerous times, look at the side plates of any of the double receiver SuperHitch's Torklift sells compared to other 2.5" receivers on the market. They reach deeper toward the front of the vehicle and are thicker so they can handle the leverage exerted by the SuperTruss. This is a complete towing system that was designed for extension use and Torklift is willing to put a lifetime guaranty behind their ratings and product.