If you look at the 5 camera placement on the headset it looks to cover a pretty heavy margin, including a wide FOV camera on the top. So you'd have to have you

If you look at the 5 camera placement on the headset it looks to cover a pretty heavy margin, including a wide FOV camera on the top. So you'd have to have your hand directly behind your back (and not at a height above your head) for it to not be able to track it, which seems like it would be uncomfortable in real gaming scenarios. John Carmack has also talked a decent bit about their inside-out tracking extrapolation tracking code to keep latency low. Their tracking predicts where your hand will be at the time a frame is rendered, not at the time the frame begins. This not only means the controller tracking will appear low latency but it also means it can figure out from the controller's sensors where it is when it can't get visual range for a second or two. So I imagine you'd have to hold your hand directly behind your back for more than a few seconds to really see the effects, and by the time your controller comes in range (way before you'd see your hand position) it should correct itself. That being said, some people with hands on did say the inside out tracking didn't do so well when the controller got too close to the front of the headset, so it's up in the air how bow and arrow type of movements will work.