After a crazy couple of days running to Flagstaff to rescue Maria, I needed some time to relax. Ran over to Lowes and picked up 4 casters and put them on my wing rack. Took two 8" x 8" pieces of plywood I was going to originally use to brace the vertical supports and cut them diagonal. Screwed these to the bottom of the wing support at each corner. Screwed the casters to the plywood. Now, I'm ready to clean the garage this weekend.