Dont you just guys who dont disclose problems such as this ? How deep does the crack go ? If its just a surface crack or not very deep I would use a piece of BVM poly ply ( proably the .015 thick), this item is also known as G-10 epoxy glass I think. You will have to sand the paint off the wing where you want to glue this or atleast scuff it up good. I'd sand it down to where there is little or no paint. You can pre paint the poly ply so after its glued on with 5 min epoxy there is no finsihing required and it will just look like a lot of full sized aircraft that have areas patched. I've used this method many times, sometimes just an easy way to repair the finish ( I use .010 thicknes for this) and other times to actually repair damage like you have.