If you are skidding logs, you might mount it in the back, or on the 3pt hitch. Otherwise I'd mount it in the front. It appears as if the front loader crossbar was mostly out of the mud. Would a winch mounted there interfere with the bucket?
You should also find a solid part of the frame below the engine. In that case, your first task might have been digging out your winch, but it would be a good place to attach the winch.
You might consider also adding a snorkel to your tractor, just in case the next time you decide that spinning the tires a little more might help.