Interesting question.
- I don't really wear shirts/blouses as they don't sit well on me.
My best suggestion is something plain in style, in a toning colour.
Therefore something that suits her figure (she'll know)
- There are some nice wrap/surplice style tops that would look lovely with a hostess length.
- Our Highland Games are often hot and I find a singlet top suitable with a cotton cardigan or bolero as Anne suggested if needed. It can be dressy or casual depending on the style
-Whilst chunky boots may not be "correct" they are practical depending on the terrain and won't really be seen. (I wear Doc's under my long skirt)
- Most women know what style and cut suits them on their upper body so use her knowledge.