Unless he builds his own, I doubt that the OP could obtrain a steel skid plate for an Outback. All the ones I have seen are aluminum alloy..... which have their own issues for cars in the Rust Belt - corrosion from road deicing chemicals.steal is heavy... and adds up fast on the bottom of your car depending on the structural integrity of your plates. this will have negative effects on MPG, and handling of your vehicle.
My recommendation is live with the lower plastic engine cover until you rip it off in a snowbank, then consider an aluminum replacement. You aren't going to damage the underside of your car in winter driving, just that plastic piece..... rocks are another situation entirely.
If you decide to drive the high dirt road passes of the Rockies, you better have metal skid plates.
Spokane WA USA