I might be able to help (I do a bit of television production) but I am curious as you mention that they also shoot video at the events that you would like to shoot stills. Do they not have enough foot candles of stage lighting to capture a good video? I shoot stills on set and get great images based on the lighting for the video (or film) alone. I understand about the flash being unacceptable but think that you could approach the lighting person (do you have a person in charge of the lights you mention above) and see if they can work with you to set levels acceptable to everyone. That includes the audience, the video camera operator and yourself. Of course the audience and people on stage will always complain about the levels being a bit "hot"...


Often times the levels of the stage lighting can be set but be careful of your white balance. I assume they are using standard quartz lamps and the color temperature will shift quite a bit as they are dimmed from 100%. Also inquire if they have used gels on the lights as that will also alter the color temp a bit.


There are several small lighting packages available that might suit your needs but I hesitate to send you off in that direction if you could work with the venue and get the existing lights to work with you. The biggest problem you will have is getting enough "pop" from the smaller portable lights to cover the width of area on each stage. If you set them up so you got coverage it would no doubt be "cross lighting" form the sides and that will create unwanted shadows (based on the severe angle of the throw and the low height of the stands). You would also need to add some backlighting but that may be difficult to do as you would see the stands behind the people on stage. Ideally strive for a 45 degree angle of the light to the person - if you are 12' back you need to be 12' tall. Going that tall means heavy duty stands and sandbags to keep them from tipping.


How large a group are the focus on stage? Lighting one person is much easier than a panel discussion of 12 people wide at banquet tables. Give me some common set ups and let's see what we can do. In the mean while google Stanley McCandless stage lighting theory. It's a great starting point.