>>280196814
I think if the purpose was known to be fbt, the half moon design of the index controllers would be better, or even a full ring around your ankle/lower leg for occlusion prevention. 
They were designed by valve, yeah, with the idea to get it up and out of the way of an accessory or be mounted to a monopod/tripod setup, but not mounted on your body so much. 
The best setup for these for fbt would be a full ring for legs+elbow and a PAIR of hip sensors on either side or front and back.