It seems that in some ways this is a second class citizen compared to
the Linux

Unlike on Linux, the defbkparm file is not a script and thus you can't
do smart things like dynamically generate the date in a similar fashion
to the technique used on linux - BKUP_FILE="gis_amc_prod1-$(date +%Y%m%d)"

I ended up getting similar functionality working by adding a few lines
to a copy of the ambkup.bat, however this feels like a step backwards.

set DATETODAY=%date:~10,4%%date:~4,2%%date:~7,2%
copy defbkparm.template
echo BKUP_FILE=servername_%DATETODAY% >>

Also, no matter how I tried, I couldn't get the LOG_FILE parameter to work.

Finally, it seems like REP_BKUP_FILE didn't work on windows, what worked
instead was BKUP_OVERWRITE.