I used to have a 5x10 Wells Cargo that I pulled a K1200LT in, now have a 6x12 Cargo Mate that I carry the Wing in. The wing is almost 48" wide and 103" long at the extremes, it would fit in a 5x10 but would not leave much room to get around it to tie it down, and you would never get a scooter in a 5x10 with a Wing. I am not sure I could get a scooter in my 6x12 along with the Wing. I am presently considering getting a larger trailer so that I can bring my cargo trailer (pulled by the bike) along and will probably go up to a 7x14 or 8x14. That will give me room for the bike (two if I choose), my cargo trailer and some storage.
My current trailer is not a Wells Cargo, it's a Cargo Mate or something like that. The quality difference is substantial. The old Wells Cargo was so much better made, IMHO it is worth the extra money they command for it. The best trailer is all aluminum and made by FeatherLite; and they are very proud of their trailers. There is another aluminum one on the internet, Tommy's Trailers or something like that. They also have a very good rep and are much more affordable. An aluminum trailer can be 40% lighter than a steel frame, wood deck one.
One recommendation, get a dual axle trailer; with the trailer weighing ~1500# and ~900# for the Wing, a 2900# GAWR trailer does not leave much room for other stuff, plus a dual axle trailer rides so much better; make sure you get the rubber torflex axles, don't mess with springs.
Good luck, Jeff
2003 Pace Arrow 36B, W22 Chassis
Ultrapower ECM upgrade, CAI, Wires, Koni FSD