If that snake were _not_ a rat snake I would be surprised. Greatly so. Does look spot on to be a rat snake. Love them around here. Only been bitten once by a 9 footer black rat snake and that was all my doing as I just couldn't get the picture I wanted and kept re-positioning it and eventually STRIKE! I simply walked over to the river, put my arm in the water so the snake's head went under and a few seconds later it released on its own so I didn't tear myself up prying it off.
When that happens to me I just clinch my fingers and make a fist and the increased pressure just pops the snake right off. Have to be careful doing that though, as sometimes they fly off like an arrow....