Hello,
Maybe this can help you to see the problem ? 
VR Helmet are a kind of scuba diving mask, when in real life you can see to 90° at your left or your right without moving your head, with current VR helmet you have to turn your head to see more than 45° to left or right. So that means that you’ll have to turn a lot your head, that is very unconfortable for the neck. Moreover, a lot of simmer not using VR use “tracKIR” that amplify head move, so they have a great advantage to see behind. See that : https://youtu.be/PVU6CE174k0
(And they have a greater FOV using 2D screen than us with current Helmets).
Unfortunately Il2 BOS is not free, you can try DCS world with the free TF51.