Hi Eric,
The next release of REW allows you to skip all the level setting etc and tell it to just use the mixer settings you have set up for the default device on your system, so that makes it a bit easier in apps like yours.
Full range tonal EQ is an interesting topic, and something I'd like to play around with automating in REW, just as soon as I figure out how to get a few more hours into each day
Main issue for most folk is having a mic that will give an accurate measurement above the midband, if they tried full range EQ using an RS meter as the mic the result would be pretty bad, assuming the tweeters survived attempts to put back what the meter's roll-off removes. Still an item on the dev list, but a long way down...