Please do not add thermocouple covers to your Skutt Kilns. They will cause the kiln to overfire because there is a delay in the actual thermocouple reading the temperature. L & L offsets their controllers to make this "kinda" of work but it will act differently when the kiln is rising in temperature vs a hold in temperature.
The KMT upgrade kits do not require any drilling. It comes with a mounting plate that is the same size as the older KM controller. Here is a video on how to do it.