IMHO, if you are going to invest 15K on a motorcycle, you'll need at least 4 wheels on the ground when you haul it. I had a single axle enclosed trailer until a couple
of years ago I saw a wreck on I-85 coming out of Atlanta. The poor guy had lost a tire, and the trailer axle caught when he was pulling off the road. So he started that day with a 25K Harley, and ended that day with 5K worth of Harley Parts.
The next day I traded my single axle in for a new double axle motorcycle trailer. I use it specifically in June, when we head down to Hiawassee, Georgia to go to British in the Blue Ridge. I haul the beer, the tents, the tools and chairs so that my mates don't have to.
It's a little expensive but it also stores the dirt bikes. I have a 7X14 enclosed trailer, it weighs 2300 pounds empty, but I can go to 7000 pounds if nessecary. Price new was $5000. Single axle was $2200.