We had this interface available for another project... dimensions are something like 10cm x 5cm. It will fit in a small box in luggage compartment with a battery and a cable to connect to cockpit rs232.
:( system is not working on Kobo. Cannot understand why! Lk8000 version 6.1r on Android smartphone runs well Lk8000 version 6.0b on Kobo with same configuration always give "unable to open TCP port" (wifi connection is ok when I start Kobo environment, how can I check under LK if wifi is connected?)
Last chance is to upgrade Kobo to 6.1r, I've seen you have added up to 6 devices... And use TCP port 6000