Nice to have someone with the real thing 
I didn’t have one as you correctly concluded. It was a bit of a stretch because these devices are fairly new and I couldn’t find any information online.
There are several options:
- Set the log level to trace. This will give you more information also what the device returns. This might give enough information for me to update the binding. Via the karaf console you can set it:
log:set TRACE org.openhab.binding.tplinksmarthome. - You could try to manually add the R270K as a lightbulb, by manually select configure a lb1xx using the ip address of the R270K. Lightbulbs use slightly different data format, and it might be the R270K uses the same. If it’s the same the rssi should work, and/or you should be able to switch it on/off.
- If all doesn’t work then the only option I can think of is to proxy with the devices and the kasa app and monitor network traffic with wireshark (there is a plugin that can decrypt the tp-link protocol so you get readable json).
If you have some useful data I can update the binding and add the data to the tests. You can send the data/logs in a private message or e-mail it to me via openhab@h72.nl