If you are planning on only taping in mono, then only use one microphone. If you use two, you run the risk of introducing phasing into your recording, and once it's in mono, you're stuck with it, no chance to save it.
I would suggest taping it in stereo, NON-LP!! I don't think the 722 is MDLP compatible, but as it is, you're losing quality with ATRAC sampling. Just put a title on each of the discs you are going to record on, and just get good at the tape flip. It's worth it in the end.
And even if you are "stack taping", it is nice to have the audience in stereo.