We're all familiar with the ADSB-out solutions, Sky Beacon, etc.
They have an ADSB-IN solution which they stress is only for the experimental category, the Sky Sensor, which is a right wing tip light replacement.
Doesn't this fit the definition of a minor airframe alteration-no appreciable effect on weight, balance, etc. (14 CFR 21.93). Why couldn't an AP/IA install and simply sign off in airframe logbook?