Best solution? Encourage everyone to record every interaction with the police. This will systematically education the police on the rights of citizens.
Just like the 2nd Amendment public carry folks with a big old riffle slung over their shoulder on the sidewalk - it educated the police & public at the same time, and nobody gets hurt. (The the latter case, jimmes get russeled by some liberals, but, meh)
What we really need is a purpose-built "CopCorder" device. Has a camera and mic that records to local storage, and streams via 3/4G to mitigate confiscation. It would have a panic button that can be configured to lock it into recording mode for a time period, until the battery dies, or it's destroyed (so it's physically impossible to comply with any order to turn it off). The storage to local media means that if THEY destroy it, they've destroyed evidence, and you probably have a recording streamed of them doing it. If they confiscate it, you continue to get the streamed recording of whatever they subsequently do/say. Bonus if it can support a hidden external bluetooth or whatever external camera or mic, so if they take it and put it in their car or something, you may still get a recording.