I'm coming from a place of mostly ignorance on handgun mounted RDS.

Right now I mainly have my eye on the Apex Tactical integrated sight mount. Is it preferable to have the optic as far back as possible, with iron sights in front like this?

Any other suggestions are greatly appreciated.

Rear sight location is preference.  Some like that having it forward of the optic means a more unobstructed view of the optic housing from the rear.  I’ve run optics both ways and I like the rear irons in front of the optic/objective lens because it’s a cleaner, more slick setup.  That said, I have shot both ways with the rear sight being both ahead of and behind the optic and I have found no discernible difference in my performance between the two.