It seems something from around the bottom/left of the ramp is probably the best option.
As for lighting, the yellowish ambient is 1/60 at f5 on 1250 ISO, but I've brightened it up here so it's perhaps a stop or so less. Ideally I want a better depth of field, as there are a lot of people and I'm intending to spread them around the set.
I have three speedlights and my stands reach about 8 feet high.
On the right (C) I can't use (any kind) of light on a stand, because it won't be high enough for people around point B: it would light them from below. Apart from the fact the ramp is sloped, the end of the stage is higher than the floor. Moving it further away would begin equate to side-lighting - as well as distributing the light more evenly across the image from right to left - I'd need a huge amount of power, and due to to numbers, some of the forty or so people would likely fall into shadow. It could be done at full power perhaps, but recycle times would be slow.
On the left of A and running behind towards me, there's a wall, limiting lighting options there. It's white and it can be bounced off, but its relative proximity to those on the ramp means they'll be lit, but those around B won't be.
Bouncing isn't a good solution either as the ceiling is high and dark brown wood. A lot of power for a limited return.