The elevators need to be remapped. You can do this by using the right click menu and using "select by geometries", then assign them to right and left aileron. You would then have to use planar mapping with the split option to get the top and bottom halves. Then place the bottom aileron halves with the bottom wing, and the top aileron halves with the top wing. Now the top will not bleed onto the bottom. This happens when you split the wing mapping, but not the aileron mapping. If bazze does not post the remap, I will ask permission to do it.