Gas or Diesel? It makes a very big difference, pulling a fiver you will want a diesel if you leave the flatlands. Service history is a big item now that I own one, did it get oil changes when it should have, fuel filters are a lot more important on new diesels so those should have been changed, and so on.
You can get the idle hours off the info center if it is equipped with that. Otherwise just the normal things you'll look for. Since you are in the frozen north, rust of course is a major item.
Starting in 2011 the OEM hitch was an option, so it may or may not have been installed. If you see 4 plastic 'puck' covers in a rectangle with a bigger puck in the center then it has the bed prep package. There will also be a trailer connection outlet on the left hand wall of the bed near the tailgate end.
They are great trucks we love ours and haven't had anything but a couple of minor problems with it: a replaced battery clamp and the 120V outlet needed to be replaced since a plug would not stay in it.