R-POD 172 spare tire

Charlie, my observation was based on what I read about another brand of extension + bike rack which advised down rating the capacity by half, plus considering the max hitch weight of less-capable TVs than yours.  Your numbers would put a TV with a 3500 pound limit (and 300 or 350 pound hitch weight) into the red zone.  One more consideration is sway, since the farther the ball is from the rear axle the easier sway can be induced.  Sounds like you would be ok.