This is a post of mine from 2005 on the same issue it is easy, effective, and almost free:
I put a couple two foot long pieces of 4 inch PVC pipe in the rear corners of my ballast box prior to filling the box with old weightlifting plates and gravel. They are just right for holding a chainsaw, a pry bar, an axe and other things I want with me in the woods. I seldomly carry a chain saw when I have the BB or back hoe installed.
Bill