Negative scaling mirror alternative

I am trying to set up an airplane model downloaded from the sketchup warehouse, and in order to mirror the wings (the imported mirror setup had lighting and texture bugs) I have to scale the wings by -1. I want to attach parts of the plane via fixed joints to the fuselage, but when I scale the rigidbody/joint by -1 it freaks out on load. Is there an alternative mirror method or something that needs to be changed on the joints.

Thanks.

I found a workaround where I put the rigidbodies in a gameobject that was the parent of the negatively scaled meshes.