Nothing wrong with that, OP.
>underwear under spats
The problem here is that she shouldn't be wearing the skirt in the first place.
What we have here is a person who obviously isn't a fan. Those are shorts. When we want spats, we want the good stuff. None of this actual modesty. We want the false modesty of a girl who can freely kick her legs about as much as she wants.
>Not having spats/shorts under skirt