Maybe not simple, but there are some advantages in putting the mic in (almost) the same place as the sound source. This is fundamentally no different from what the echo canceller in a hands-free speakerphone does. They can work very well in full duplex so long as the speaker and mic are reasonably linear. The echo canceller knows what the drive to the speakers is and can deal with frequency response variations.
Cheap electret mics are very linear over a reasonable range of sound pressures. Their noise floor is not anywhere near as good as studio mics, but is probably good enough for use in a normal room. They don't usually cope very well with high sound pressure levels, but again this is unlikely to be a problem in this situation.
John