I bought a mirror from Deere I think it it was off a 7xxx series tractor that works great on my 5488. Mounted it on a 2" angle iron that was bolted  thru the pillar that runs up in front off the door. You have to remove the molding that covers post and trim it a bit for the angle iron to go thru.

I like it you can open the door without hitting the mirror, it's light enough it doesn't bounce around, folds back without damaging it, it's easy to extend out and it stays in place when you want it to. At the time I didn't think theprice was out of line. works better than anything else I tried.

I can take pictures and post if you would like