I agree with Shodobe, (and who wouldn't), most every Appy I've ever seen done a Rue (sp?) retractor, a devor or two, maybe a rich, and good scrub tech to hold should be all you need.
Now, that said, if the pt weighs about 400 lbs, or something like that, well that's different.
There's no way I would open a BookWalter without thinking twice.
It's way to heavy to just be tossing it out there, and think of the clean up time.
I assume your doc is just used to having it, or having more people to retract, no extras, open the BookWalter, I guess.
We almost never open the BookWalter unless it's something bad like.......oh wait, I'm on call,,,,I'm not going to say any more....bad luck ya know!!!!