The Reverb G2 is lighter and supposedly more comfortable than the Index, and it has the exact same audio solution. It also has better resolution and clarity thanks to 2160x2160 to both eyes and superior lenses. Since you already have the Knuckles, you'd have the best possible VR setup if you swapped out the Index for the Reverb G2 and used the Knuckles with it (which reportedly works perfectly well).

Sadly, I think Bridge Crew is nearly dead; the last time I played, it was a struggle to get a full crew together. Some of the most fun I've had in VR was in that game, though. We'd just need two other people.