Hey there!
All you can do - is what you can do.
You guys shooting the .5? Have you thought about a dose you might be comfortable giving when you are presented with one of those BGs that are less than 200? Some times we did a skinny .5....something that was less than .5 but more than .25. I had an idea of that both of those doses would do, but this way I didn't skip a dose. This way he got a consistent dose and I got practice at shooting lower numbers.