Aggression aside, I think a simpler/safer solution for both you and your turt would be to build a small nesting box (you can use a small rubbermaid bin) and attach it to the top of the tank so she can get in/out as she needs to. How would you feel if your turtle didn't wake up after the surgery? I mean there are risks even with simple anethesia (sp?)
That way, there would be no need for whoever's taking care of her at the time to know anything more than the basics. Just check for eggs every so often and if there are any, chuck'em. Good luck with whatever you decide.
