How much money we are talking here for the DPA stuff?
I can see that the cell phone idea sounds fine, but maybe not yet. At least using Android.
Maybe a Tascam DR-05 is a better ready made option, with fewer compromises.
Looking at flat-frequency lavaliers on B&H, DPA seem to be around +$500 each, but there are other options for less money. Like Countryman.
I have some lavalier that I used on my wireless Lectrosonics that I could plug in the Tascam DR-70 to see how they sound for music, The DR-05 preamps are certainly poorer in quality, but maybe not that much.