Thanks for the samples, I'll try and give them a listen maybe tonight or this weekend.
I don't expect the exact forward spacing of the center mic to be super-critical here, and it looks like a reasonable arrangement in your photos. In general, use a bit of forward spacing for the center microphone and don't worry too much about it. In one sense it may be advantageous to arrange things so the Left/Center mic pair is perpendicular to an imaginary line pointing at the left PA speaker and the Center/Right mic pair is perpendicular to an imaginary line pointing at the right PA speaker, which is easy enough to visualize and apply at setup.
May not be necessary, but if you'd like to play with slight modifications to this arrangement the next time out, I'd try increasing the spacing between Left and Right microphones when the center mic is in play. One way to know when such a 3-microphone arrangement is close to optimized is when the Left/Right pair sounds a bit over-wide or a weak across the center when listened to in isolation with the center channel muted, but the 3-channel mix is well balanced with the center channel unmuted. That's not critical to making a good recording which benefits from the center microphone, but will tend to make the best of the combination of the 3-microphones.
More technically-
In terms of imaging, forward spacing of the center microphone is mostly relevant when playing back the 3 recorded channels discretely over 3 speakers across the front, in regards to getting a precisely accurate image distribution across the boundary between the left-center speaker sector and the center-right sector.
In terms of achieving a low value of diffuse field correlation (which is what makes the ambiance and reverberation in a recording sound natural, open and enveloping) significantly greater spacing is required (a few feet, rather than a few inches), which when applied to how far forward the center microphone position would likely require application of delay or visual alignment to bring the direct-arriving sound from the stage and PA back into proper coherence across all three channels. Increasing spacing between the Left and Right microphones won't require additional delay or visual alignment to keep the sound arriving from the stage/PO coherent while likewise decreasing diffuse field correlation, and even a slight increase helps achieve better diffuse decorrelation, up until it gets too wide such that the center microphone starts sounding more like a separate island of sound and the good smooth, solid image distribution between speakers begins to suffer.