I needed a trailer that was taller so I could carry a lifted golf cart and it cost me the same to have it 6.1/2 or 7ft so I went with the 7 ft and I am glad I did, I spend a lot of time in mine esp in the summer and it gives me plenty of head room.
I think it will be hard to find a used one that is taller than 6ft but if you are willing to look and wait you might find one ? but I think a lot of people want as much for a used trailer as if you bought one new from a factory? that is what I found when I was looking.