Maybe its been mentioned...
There is something to be said for driving with the tow limits of your vehicle from a comfort standpoint. I drove thousands and thousands of miles well over the then current trucks rating and I was always flat worn out when we stopped.
In June I did a quick run from AZ to NE OK and back (three days total- about 2100 miles). Picked up nearly 20k pounds of steel in OK. It was an easy run because the trailer and truck were were within their respective ratings.
So yes- you can do it and relatively safely. But it is harder on equipment and harder on you...