Little Foot: In looking at the various replies, and reviewing the fence post idea, if you want some figures, I can tell you the forces, stresses, etc. having been a civil engineer. The log or wheel ideas transfer the horizontal pull to a vertical pull, but don't give any mechanical advantage. The 3" diameter pipe with a foot on the bottom and "U" does give some advantage. The fence post thing however, can be beefed up by making a simple truss. There is one other idea that I have used many times for pulling stuck vehicles, partly cut trees leaning the wrong way, etc.. It is the old fashioned block and tackle. However, you need an anchor for the end not hooked to the tree. The mechanical advantage is the number of lines that you can count running between the pulleys, also counting the pulling line. With double sheave pulleys, this can be a factor of five. Using nylon rope or similar, be aware when any end, either at the anchor or the stump, breaks, you have a vicious sling shot. So, I manage to keep my pulling tractor away from the direction of the line between the anchor and the stump. Paint the chains bright color, because then they will be easier to find if they break. I have lost a few. If you use a stout tree for the anchor, I use a big wide nylon strap to avoid damage to the tree. If you tie any knots in the rope only use a bow-line, since that is easier to untie. For pulling from the draw bar with rope, I made a cleat to fit there, so no knots are needed. I hope you are aware of the danger of pulling with 3 PT or higher, a back flip is possible.
