Warp sketch on the inside face of an airfoil

I need to wrap a sketch onto the inside (top and bottom of the rear section) of airfoil seen here.  I have been successful in warping it onto the outside of the sketch but the inside is not working.  I have split up my extrusion to allow me to select only the inside face of interest but I am unable to select the inside face when I want to wrap the sketch.

Thanks in advance,

Austin.

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