Hi John. I think that metal extension is a skid to prevent damage if you drag your tail. My Safari has one too and it sure won't hold the weight of the coach -- it will deform in fact -- ask how I know...
I've seen the 'jack point' stickers on belly wrap. Anyone is lucky if they have one or two that haven't blown off over the years. The belly wrap obscures the fairly narrow frame and these 'jack points' generally should be used only for stabilizers. Forums members have posted photos of a jack impaling through their belly wrap when they attempted to jack on one of these seemingly designated areas.
Jacking to remove a wheel? Place the jack under the exposed, flat heavy frame that the axles are attached to.
I carry a bottle jack with me if ever a road hazard should flatten two tires on one side. I carry a wheel ramp for the other 99% of situations. Keep the trailer hitched to the TV and pull or push the good tire up onto the wheel ramp. The other axle on that side will be suspended in mid-air all ready to work on. Set the emergency brake, put down a couple wheel chocks and you're on your way. Very simple!