In reply to The Lemming:
my first thought was... you need to learn how to say no, lol
that's quite a project... is it a full song / single or just a wee (30 second for example) promo?
if you can keep the scene reasonably well lit, then the gopro would probably be "fine" for wide shots. i say fine but the barrel distortion is so much more noticeable indoors than out because of the abundance of straight lines inside. go wide and crop?
does it have to be done in one take or are the good enough to play the same thing several times in a row the same?
you want to record the sound all the way through at lease once i'd have thought, sound is actually much harder t oget right than most of us camera pointers like to admit. hopefully the sound guy can help, might be worth renting a wee zoom recorder and taking a line straight out the mixer as well as using the ambient sound from your videomic
if you look at videos of similar bands for how they are often shot ie wide > mid > tight > repeat
other than that i'd suggest maybe borrowing one of them and practice on them in your preferred location (or stunt doubles / stand ins if you can't get the actual band)
shot from different positions and playback immediately to see what works and what to tweak.
GOOD LUCK!