This ^^. If you don't' 'want to dump a bunch of cash a 16 ft landscape trailer will get the job done and be really useful for other tasks as well. I built one 20 years ago and that thing has been used so much it's amazing. Would be great for your setup.
I think he'll need at least 18ft, My 790 with loader and 5ft bush hog attached is just too long to sit on a 16ft deck. I have to let 2ft hang off one end or the other, or some of both. Usually I back it on with the bush hog raised and get the heaviest part of the tractor over both axles. Then drop the BH onto the front rail (my trailer has 12" sides). Once I raise up the 4ft drive on rampgate, I lower the bucket onto the top of the ramp. Ugly but it works. I keep saying that one day I will sell this 16ft trailer and get me an 18ft, or possibly a 20ft trailer. See the pic I added (that's not my current pickup truck though).
One other thing to look for though, make SURE you get a spare tire with the trailer. It's also essential to get one with a storage box on the tongue, imho. Need a place for all those chains, chain binders, wheel chocks, etc...
If you get a flat bed equipment style trailer with no sides, preferably get one with stake pockets so you can at least make some sides out of wood to use for temporarily hauling dirt, gravel, firewood etc, for those times you're in a pinch.
I prefer a trailer with permanently attached ramps, preferably with supports on them so when you drive up on it, it won't pick the back end of your truck off of the ground. My next trailer with have supports on the ramp!!! Also, being attached makes them less likely to walk off in the middle of the night.
Lots of other good advice in this thread though. :thumbsup: