Yes they are but at what cost. You would be better off with a truck with way more capacity instead of nearly maxed out both for safety and longevity of the pickup drivetrain.
I towed for many years with a truck that was at maximum capacity and it wasn't until I finally got a truck with way more capapcity to pull our 5th wheel that I realized just how lucky we had been all those years. Several downhills with brake fade, uphills with overheating, panic stops...we were lucky nothing serious happened.
This new truck stops the 5th wheel, pulls it up hills and holds it to a safe speed on downhills unbelievably better than our old truck. I no longer have white knuckle drives...towing is very pleasant.
Get as big of truck as you can afford...for better safety.