Can i do audio monitoring with wireless headphones with a field recorder?
I see no reason why not. You'd just have to make sure you find a transmitter that's battery powered, and small enough so you can bundle it with the micro-recorder. 

The question is; is it necessary. Would you be able to do anything, such as stop the event/filming, if there was a problem? Secondly; the feed you're monitoring is only going to tell you it's listening, not recording. 

We use the micro Tascams with Lav Mics for some events. My recomendation is:


Double Up:  Two Micro Tascam Units
Double Lav Mic Clip
Test Test Test your settings; input levels, auto gain vs manual, bit rate, etc, and get them both setup so you wont overmodulate. 
Run one slightly cold. Lower the gain / input on 1 mic by 5 db. So if the speaker gets really loud, you have a lower gain recording. 
Record in PCM 24 Bit if possible. You can then use compression in post to get super even audio. 
Use black gaff tape to tape OVER the hold button after starting the unit. This will prevent the units from having both a button pressed, as well as the guy turning off the hold button - it's happened to me. 
When you start the recorders in the field, at the very start; talk right into the mics, and say; DATE, TIME, EVENT, PERSON THE MIC IS GOING ON, ETC. 
Then tape HOLD and LAV them up. 


I'd do double mics over monitor, but not sure if that's what you want monitoring for.