If you don't want to mess with shifters and ders and other big changes associated with triple conversion, you could temporarily add the triple crank and just tweak the existing der to switch between the two inside chain rings. I'm doing the same thing on a project where I swapped the outer ring to a CF chain guard and use the remaining 42 as my top chain ring, and swapped the inner 30 down to a 26.

But I also agree you might want to try what you've got first.