I want to record a live show with my Tascam 424mkII.

I know nothing about the dimensions or material of the room, but I do know that the main outputs for the source of the music will go through channels 1 and 2 on the 4track, then out from there to the monitors for the crowd. All the music is electronic, daisy-chained together on its way to those channels.

Then, I want to have mics plugged in to channels 3 and 4, and I want the tape to pick up a stereo signal of the sound of the audience along with a little of the reverb of the sound of the music reverberating. So basically the end result will be mostly the dry signal of the audio performance with a little atmosphere of the room and applause or whatever.... I'll be recording all four tracks simultaneously.

All I have to work with is a pair of SM57s and a couple mic stands. Should a do an XY configuration and points the mics at opposite corners on the other side of the room from the middle of the stage? Or should I put them on either side of the stage and point them at the audience triangularly?

I'm not concerned about the mics feeding back in the sound system, because I'm pretty sure I can bypass that on the tascam so it won't be heard during the show.... any help is appreciated