I have LOTS Of intact females in class with my intact boy. We've only had one issue and that was when he was in a down stay in a corner while I was being a post for a figure 8. A girl with a UTI had sat there earlier and dripped quite a bit and they didn't get it all up. So...that was fun. It was toward the end of class. I tried to work through it and mostly got him in the end, but honestly, I wish I would have crated him in a corner and played with someone else's dog in front of him! That's the only issue we've had other than very occasional air-sniffing toward a girl or two, and I tell him to leave it.
I would work on focus with him during distractions. There's always going to be something better than working even when he's neutered: pee, poop, hotdog, squirrel, etc.