Not sure what you are seeing with mirrors that a person wouldn't see out the front windshield, thats one one the biggest advantages, better field of view, not sure how mirrors suddenly let you see around corners.
A jeep is narrow, you cant see down the side of the trailer when backing straight. With mirrors you can. Thats why shunting rigs in trucking yards sight severely offset to one side, and have a mirror to see down the other side.
In a jeep, without extended mirrors, all you see is wall. You dont know where you are going. Forwards or backwards.
Yeah your trailer reacts faster, but if you cant see, it dont mean crap. 15 years as a truck driver I've had lots of experience backing crap up. Mirrors are king, and approach is 90% of the back up. Cut in on your left side whenever possible.
Trying to shunt blindly while starring at a trailer wall will just make you completely dependant on a spotter, and if said spotter doesnt know how to spot with cut and follow directions you will spend the day frickin' around trying to do something you could do yourself in 5 minutes with some extended mirrors.
You keep posting like reaction speed is most important thing to backing crap up. It isnt. Visibility and preparation is just as important. Taking away your visibility just so you can turn faster (which isnt even required in this situation) is just dumb.