I have had a truck and camper since 2011. Often towed a 7000 flat bed with trailer behind the camper. I used the Torklift dual receiver, with the Super Truss extension. Never an issued.
3 years ago got a new camper, and a new Super Truss. I have since got a new truck and bought a new Super Truss.
I have my 2 year old, used once, extension on Market forum. Hope someone can use it for half what it cost new