This ^^^.
Small tractors are prone to tipping to start with because of the narrow stance. There was a recent thread about a really neat grapple attachment for tractors that had a chain on top for lifting and another chain hooked down low for the pulling. Anything above the axle for pulling with a tractor is asking for trouble. Especially if it has large rear tires which amplify the problem.
I almost purchased a winch skidding setup for my tractor but had second thoughts about tearing it up in the woods and working on uneven terrain. I decided to build a small machine just for skidding that also had a 6 way blade for cleanup duty and a low center of gravity. Started with a Vermeer trencher and a hydraulic winch. Added a boom, foamed the tires, and chains.
<img src="http://www.tractorbynet.com/forums/files/build-yourself/446918-3-point-log-lift-skidder-img_0091-jpg"/>