Brett,
You could probably do fine with a smaller trailer depending on what attachments you plan to bring with you. I haven't measured my tractor, but it weighs about 1800 lbs. as it comes from the factory. So, our tractors are probably similar in length.
Assuming our tractors ARE similarly sized, here is what I would consider when deciding on what size trailer to get:
1. A ONE axle trailer: My trailer is 16' and has two axles rated at 3500 lbs. each. The trailer weighs about 2000 lbs. (or so the trailer store tells me). I think 3500 lb. rated axles are fairly commonly used in trailers.
If you get a single axle trailer (rated for 3500#), short enough to just fit your tractor, a trailer weight of 1500 lbs. or a little less sounds ballpark. It should carry your tractor, but nothing more, due both to size and weight constraints. The only time I would have just my tractor on the trailer would be to take it somewhere to pick up an implement. Most of the time, in transport, there are already implements hanging, usually front and rear.
2. A TWO axle trailer: If you ever think you will transport an implement with your tractor, you will need more weight carrying capacity and possibly more length. Something like a post hole digger or MMM doesn't require much extra weight capacity or length, but many commomly used impements do need more.
With front loader and box blade in place, 16' is just right. With front loader and backhoe, 16' is right at the limit, and is almost too short (I like to rest the hoe bucket on the trailer). A 16' trailer will not seem too long once you start using it.
The weight of implements and the trailer length to accomodate them will require a second axle or you run the risk of seriously pushing or exceeding the ability of a single axle.
Lasly, even if you can comfortably get along with a shorter than 16', single axle trailer now, your needs could grow. The tractor can handle that growth, but the trailer couldn't.
Hope this helps. By the way, be sure and get brakes on your trailer. I was skeptical about the ability of an electric brake on one of my trailer axles, but not anymore. Traveling with a load is safer and it helps my peace of mind.
OkieG