I might backwash every other night for a couple weeks and test before the softener for iron. If the filter gets all of it go back to the 3rd night and see if it does and if so then leave it.
Run your outside faucet to get rid of any rusty water when you come home Monday instead of getting it into the filter. Maybe every day for a week to make sure all the rust is gone in the main line. That will help flush the line of rust build up until you shut off the sprinklers for winter. And any time you see rusty water.
You have a Fleck 5000 control valve.