I definitely use the tape and battery changes as an informal break time for sure. I figured that out very quickly!
I think I have a great working relationship with the producer so in terms of trust, it is definitely there. I get into trouble when it is towards the end of the day and the posture starts to weaken and the shots suffer because of it. It sounds as if job specific conditioning and exercises like you and a couple other camera operators have suggested would really help. I'm going to have to try those as soon as possible. Thanks a lot for the great advice, it sounds like you have a handle on the reality shooting, or as much of a handle as is possible in the reality world!