ditafm-output.ini and PDF output for different situations

I'm using a DITA 1.2 structured app and templates that I've set up. I'm generally happy with the output that I'm getting now, but I've also come to realize that I have two different situations for PDF output--in situation one, I need to set up for printed books, i.e., facing pages, keeping chapters starting on right-hand pages and so on. Situation two is for electronically-distributed PDFs that are NOT books--files that customers might print themselves, probably not double-sided, so I don't need facing pages with the associated blank pages in the file, and so on.

I'm using flags in the ditafm-output.ini file to control the pagination for the printed book in my output. Both situations currently use the same output templates, though I may create a single-sided template for situation two. That's easy enough.

My question, then, is this: It seems to me that I'll need two different ditafm-output.ini files for the two situations. Is there an easy way to switch between them? Output seems separate from the structured application, and I don't need or want two separate apps.

The best I can think of at the moment is to create a second ditafm-output.ini file with the settings I want for situation two, name it ditafm-output_foo.ini and change it to the "real" name when I need it. This, of course, introduces a potential overwrite disaster. Naturally, I'll keep backups.

Unless there's a better way??