Layers always works. I don't think boots are inappropriate. I find shorty shorts more offensive than footwear. I made DD a pair of 50's style shorts out of op shop jeans because I was so horrified at the shorts that wear available this past summer.

My DD has always had a very alternative view of fashion, even at 5. So a lot of parents might not approve of her style I personally have never found it inappropriate. Even now with her new found love of 90's grunge (skirts, textured stockings and doc martens) I still don't see that as inappropriate. I have more issues with off the shoulder tops and short shorts, leggings as pants etc. But that's my inner prude coming out.