The way I would do it is to generate two symbols for your dates, then use those. Requires two steps (the first being tiny), which you don't seem keen on.
Another way would be to include your dates on at least the first record that is presented to OUTFIL, and then pick up the information from there.
You cannot do it with DATE or a combination that I know of to reformat without all elements of the date (day, month, two- or four-digit year). You cannot just magically get it to do the previous month.