Do a search on this site for trailering. This has been discussed at length, with lots of good information being shared about trailer length, wieght, tow vehicle considerations, trailer brakes, chaining down the tractor and more.
To get a better idea what you need, supply more info too; which BX, what attachments, how long is it with those attachments, how much do they weigh, what will you tow with ect. The more information you have, the easier it is to narrow the search.
I personally like my 16' flatbed 7000lb trailer. My B8200 is a bit bigger than your BX. I have found it hauls my 2500lb tractor easily, has room front and back for load balancing. It also works well for lots of other stuff. I have hauled Cub Scouts in parades, cars, other tractors, 16' and 20' pipe and lumber, firewood, concrete retaining wall blocks and more. It is amazing how many uses there are for a trialer /forums/images/graemlins/shocked.gif