I'd start with a 16' tandem axle trailer minimum. If you ever do any decent yard cleanups, you'll be glad you had the bigger trailer. And IMO, the longer trailers are much easier to maneuver. I could back an 18' trailer through a slalom course. The smaller trailers are also more sensitive to bumps and potholes and will beat on your equipment more than the heavier/larger trailers (our roads are crap in Ok). I also prefer having a brake axle.