It has been my experience that if you have a surface or an object that FR uses for flight like a stab or a control surface, it is not a good ideal to try to use them as a SKID.
Example . If a rudder is touching he ground like a skid and you keep moving it back and forth the planes tail will start sinking until the fuselage COLL hits the ground and it crashes. ( explodes )
I would make an object like a wire skid and give it a COLL mesh. Link the skid to the fuselage, do not confine it with the fuselage.