If you have time and the engineer is willing, AND the console is capable, you could run the mics up the snake and into two unused channels on the console. Then route those two channels (panned) AND the mix from the mains, groups, or each channel to a seperate output and into your recorder. Not all consoles can do this, not all engineers will be willing either. It's either this, or get a 2nd mixer and take an output of the FOH console mix with your mic signal on the 2nd mixer. Mics onstage will help avoid noticable delay and you cannot remix the levels once this is on 2 track.