Consider some kind of iPhone (Android?) based system. I'm not sure what the hardware would look like, but probably quite a bit less bulky than a recorder. Figure out what the oldest model is you can use, and dedicate that with no service plan for it.
Please. That is not the answer.
How about a pair of DPA 4060 with the new d:vice directly into an iPhone ?
Tech evolves, and once crapistic solutions sometimes become viable options. I expect the DPA system will be an perfectly acceptable answer in terms of sound quality, and should be easy to stealth. We'll find out once it is actually released. Not at all thrilled about the radial input configuration for pocket-ability reasons, but everything else looks
good excellent for this application. As I posted in the dedicated thread about it, I'd be an early adopter if they made a 4 (or more) channel version, although I doubt that will happen. Personally I'd suggest buying an old iphone for use with it, dedicated to recording only.