I had a look at the dress code for highland dancers of the SOBHD (Scottish Official Board of Highland Dancing). The dress code does not get updated very often (this year was the first time in 10yrs or so) and, I imagine, could be used as a reference point for 'preserved' kilt lengths.

The guideline for both male and female Premier dancers state:

Kilt: Any clan or district tartan is acceptable. The length of the kilt is to the top of the knee.

No height for hose is stated, but the general fashion is to the bottom of the knee.