Basically, RSS, RO, RP0 and related mods running in 1.8.1 do not have KCT, use the KCT module built in RP0, and do not have Kos.
In my case, I can directly build the vehicle in VAB and add KCT. When starting construction, I can exit the building to launch, but once I save and open a saved vehicle, I can't leave the construction page (I can still switch between VAB and SPH)
Secondly, I don't know how to upload files in this forum....