My suggestion would be to consider running the se8s in nos, din or ortf, ideally setup about 10’ back from the PA speakers to allow you to capture the vocals clearly. I would choose the option that gets you closest to having the mics on axis with the PA.
The reason I suggest being in that position is to be far enough back to capture the vocals, but not so far that the reflected sound is too powerful. It will also support improving the music to crowd ratio.
The suggestion of the cardioids is also to improve the ratio of reflections and crowd noise to music.
Finally, the suggestion of NOS or ORTF (or DIN) is to narrow the stereo recording angle, effectively giving your recording more “width” on playback, which will also help with the reflections vs. Direct sound. Both of these improvements will become even more important as you move back from the “ideal” distance from the stage due to any required logistical compromises.
My two cents, I hope it’s helpful.