I will reply to my own question. Mostly, export map didn't really work at all in Pro 2.3, but it works exactly as advertised in 2.5 with the writing of world files, all that good stuff. Also, has a nice "Show preview" button to make sure you are getting what you want. I'm looking into automating this process and setting the map footprint via controlling the Map object's "extent" parameter but that might not be the way to go.
In times past, it seemed that ESRI support people monitored these questions and gave simple helpful advice. Now these questions go unanswered.