Can't really call the OEM rear diff guard a skid plate. It's only a small piece of thin steel that covers the rear diff. Protects against dirt or grass mounds but if you hit a rock it may be crushed. Most aftermarket ones provide much better protection and can be used as a jack point as well. As you plan to go in the bush some why not just go Primitive and get a jack point as well. As easy to install as OEM.

 

I think the OP is calling the transmission skid-plate the rear plate. The transmission is an expensive part and I like having a skid-plate protecting mine.
When things start rubbing on the bottom of my car, my triple-plates from Primitive Racing make me smile.

The OEM covers on my model are plastic.

 

I'm with CO17 on this - the OEM can not compare to a quality aftermarket set of plates... I have the Primitive triple pack (front, center/trans and rear diff) on my Forester and I can tell that the times I hear a "ping" or a scrape along the bottom side is my proof in money well spent.

From what I can see online, the front (silver, aluminum) and rear (black finish steel?) are there and will provide some protection - maybe even enough protection for your needs.

But there is no coverage for the center - the CVT and the power distribution unit (similar to a differential). For that, you need some aftermarket designs.

 

Compared to the cost of replacing a transmission, $239 for a transmission skid-plate seems cheap to me.

Primitive Mid-Armour Plate for Subaru Wilderness

I hope the Wilderness is the Forester of your dreams, after this wait.

The planning while you wait can be fun and expensive.
Enjoy

 

also look at fuel plate skids from subaru . i got those after my primative kit