Four wheel drive is a must when towing on snow and ice, we use a 400CC Suzuki King Quad with a pintle hook mounted on the front. Just make certain that you don't exceed the steering limits of the nose gear, when maneuvering around the ramp.

Might i suggest something with a drive-shaft design for powering the wheels? Most garden tractors and lawn tractors are driven by rubber belts. I'd think that plane would be too heavy for a lawn or garden tractor. The idea of using the kind of machine as told by the other respondent, would be much better than a garden tractor. Most garden tractors as advertised today, aren't near strong enough for what you propose. They are usually just a step up for the average home owner. More or less a selling gimmick.

search for "aircraft tug" and you will find many designs that are made for this. Some are battery powered and some are gasoline.