Power plane. Most have a 45 degree V for chamfers, make a pass or two with that then a few using the outer part of the base plate.
OK, it's not the most traditional way of doing things, but it's quick. Finish with a drawknife if you need a transition from square to octagonal.
I feel the power plane is vastly underestimated as a tool, even cheap ones are capable of doing impressive work with a bit of practice.