In very low light I have had great luck with a two step developer... I used basically very week D-76 (3:1) for 2/3 the time inverting 10 secs every 3 mins and than a bath in Borax for the same amount of time with no agitation. I tend to use fairly warm water (about 72) but you could do the same thing with perhaps a 1:1 at 60 with finer grain. I stop (not that there is alot going on) and fix normally.
I think this is 3200 with PP'd colours painted in... the light was one small work light and a pen light... so far less than you will have on stage...