Well, the tractor alone is greater than 10 feet long, add the loader length out in front, and a mower on the back and you're probably looking at a minimum trailer of 20' but preferably a minimum of 22 feet would be better.
With all that weight, tractor is probably 3500#, loader, not sure, mine is about 750# if I remember right, and a mower could be a couple of hundred to several hundred pounds. You would not want to load your trailer to it's max weight limit, so I would say you could "get by" with two 3500# axles but 5,000# axles would be better. Remember that one must deduct the weight of the trailer from it's max LL, and what's left over is the max in equipment you can carry. I never want mine right at the top of that "limit."
John