The geese own the Towpath when they are raising their young. At a minimum, they'll hiss at you, but I even had one takeoff and chase me for a couple hundred yards. Sometimes you have to stop while they gather up their young and slowly move aside. Can't figure out if they are really stupid or really smart.

My commute happens to be all pavement, but I cannot imagine any surface that I could ride a bike on where I would forgo using a rack & panniers in favor of attaching my load to my skeleton.

Re: geese, I hold my line and do not slow down for them (I do cut the goslings & their parents a break in the springtime though). They are like bees and can smell fear. Plus, though not the brightest creatures God did make them intelligent enough to get out of your way. But that is not to say that they won't test your resolve on the subject.

When riding aggresively, I put backpack on my back and go.
When taking it less fast, I put backpack on rear rack and tie it with bungee cords.

Considering buying panniers for packing more stuff on paved road rides (work commute, groceries etc).