Surely, someone has asked this question before, but I couldn't find a thread:
Could one use a Y-adaptor at the GL2 stereo input, taking the output from one or two Samson Micro 32 receivers, attenuate in the camera, and sidestep the BeachTek or MA-300?

Should work with one wireless to each channel. Set the wireless to mic level output, and you may need to set the GL input to the MIC ATT setting.

Manual gain should result in better sound by virture of not having the sound level in one channel influence the level in the other channel.