Teach them to look for the coach after they cross and you'll do fine. If you want to get cute and show you know the rules better than the umpire you will get called out at some point. It may not be the right call but while you can turn left according to the rules some umpires will take that as an attempt and call you out. It's a judgement call that you can't protest and just not worth it.
You are right and if you want to protest you have the right to do so if they say that. Maybe it's just me but I don't try and do things that really don't give me an advantage but can cause me problems.Wouldn't that depend on what the umpire says?
If he says "she made an attempt toward second," you're screwed, of course. If you go out and ask "why did you call her out?" and he responds "She turned left," that seems like a misapplication of the rule. I think at that point, I'd probably ask them to get some help because simply turning left doesn't matter, but I suspect they probably wouldn't bother.
You are right and if you want to protest you have the right to do so if they say that. Maybe it's just me but I don't try and do things that really don't give me an advantage but can cause me problems.
We generally coach players to round 1st base on a single and stop about 8-10 ft from the bag. Similar to a lead-off. My understanding is that the next move the runner makes is a commitment either to 2nd or back to 1st. Can't dance around out there!