Mirrors on tractors.

Best location is above your eye level, just outside the left side of the hood area and forward of your eyes 3 to 5 feet. Whatever it takes to see over your left fender to be able to see anything back there. On my D-17 XT it was just above the hood and 12 inches out from the hood. A big round convex truck mirror is best.

I think the biggest problem will be getting them strong enough to withstand the shocks when you aren't on the road. Without a cab, they will reduce visibility when you are doing something in the fields. I am betting vibration could also be a problem.

At least you are considering them for Use where most that have tractors with them on here seem to not ever use them Oblivious or Ignoring to LINES of traffic behind them.

I bought a set of magnetic mirrors off of Ebay.  They were around 50 per set and are very well made and the magnets are very strong.  I set one on the top of the right fender on my 160 to try it out.  Not much vibration and it sticks well.  I tried one on the roll frame of a 5660.  It sticks very well also and stays put.  I am ordering more for other tractors I have.  With the magnetic mount, you can move locations or move to other equipment.  Just look them up on Ebay.

All our farms tractors have mirrors.even mounted to the cab they have vibration and if you dont retract when you get to the field they break off. When I'm riding bicycle I have little mirrors clipped to my helmet visor. You could just as easily clip to your hat.