Make sure you have enough ballast weight on the front of the tractor if need be. That is a lot of weight suspended by a leverage arm far out from the back of the tractor. I am sure you will know right away if you need more weight in front as the tractor front end will rare up.
Best bet if things are iffy would be to raise the mower with the boom just enough to get the weight off the trailer and hold it until you can drive the trailer out from under it and then set the mower down. The you can hook it up to the 3 pt. hitch and move it where you want.