Harbor Freight has a spare tire bracket that looks like it will bolt to the side of the trailer. If I built a kit, it would look a lot like this and cost more, so you might as well try this one:

http://www.harborfreight.com/trailer...ier-93341.html

Be sure to locate it where the bolt heads on the inside of the trailer wall will not interfere with the wing dollies or the wing itself. I recommend using round head carriage bolts. It may be obvious to most people, but do not drill through the trailer side without taking your wing out first.

Mine is located just in front of the right fender. I have not seen any evidence of bending, but try to support the tire in such a way that it is not cantilevered. There are other types Like this one:

http://www.etrailer.com/Trailer-Carg...ne/413200.html

It can be mounted vertically, so the load is spread over a larger area of the sidewall.