In a big yummy space like that, I would definitely prefer a Decca Tree myself. Spot mics
are a good idea. Doesn't look like you have 3 omnis so the AKG perception for ambience
would probably be best as an AB pair.
By "non representative" do you mean- it
won't be the same group as on the night? That's actually OK your main issue will be direct
vs reflected sound. Take a lot of care with that (although I get the impression you
already know that).
Synths and pianos for Kontakt