The kind of "L" bracket I am thinking about is the type used for shelving. I would look for the longest ones available (18 inches minimum), then use the wire rope clips in 2 places to attach it to the cage. In fact, I would probably use a pair of brackets on each long side of the EB spaced apart near each corner, which would give you even greater stability in the wind.
Raybo
EDIT: I just noticed in picture #9 that you have the casters on. I would definitely remove them, as they make it easier for the EB to tip with your cage loaded with fruit. You want as stable a base as possible.