The first thing to do is sit down for a few minutes, and search this site for "trailer". There have been some very good discussions about sizing trailers, trucks, brakes and hooking it all together, over the last 4-6 months.
Start by getting all the data for your tractor. You have the basic weight, but get a little more info. These are some of the things I considered when getting my trailer:
- overall length with the biggest/longest implements mounted
- Weight of tractor
- Weight of implements(I often take a couple when I transport, ie tractor with the bushhog and scraper)
- Tool box
- Fuel cans
- ice chest(lunch and drinks)
Now you can start to size your trailer, and think about whether it will work with the GVWR and GCWR of your truck too...
Based on just the weight of your tractor, you are looking at a 10k trailer. My 16' 7000lb trailer weighs 1600lbs, with a cargo capacity of 5400lbs. Guestimating that a scraper or mower for your tractor would be in the 4-500lb range, you would be pushing PAST the capacity of my trailer. Your tractor is much longer, so you would be looking at a 18' or longer trailer, which weighs at least a few hundred pounds more than mine. With that in mind, a 18' 7000lb trailer might wigh in the 1800-1900lb range, giving you barely 5000lb capacity.
When looking at a trailer, make sure you get a spare tire, and a lug wrench to fit too. You can probably use the jack from your truck, or even unload the tractor and use the FEL. But, it doesn't help if you don't have the spare tire, or a way to get those lugs off. It would really be a bummer to have to leave that tractor and trailer on the side of the road while you get your flat repaired.
Make sure you have plenty of tie points. Mine came with ok chain tie points. I have added rope hooks, as my trailer gets used to haul all sorts of things besides tractors. It's interesting all the uses you'll find for a trailer...
Get plenty of chain and binders. Chain and bind at all four corners and over implements. There is a lot of debates about the requirements, but if you chain and bind all four corners you'll be legal in 50 states... And, a couple hundred dollars of chain and binders is really cheap insurance for $20k of tractor, $2500 of trailer.