There is no substitute for someone who's intent is to try and get away with things, and someone who's intent is to serve a cause, be of service, and not get away with anything.
So really, we should build a system where the intent of transparency is paramount, not just transparency itself.
Two things immediately come to mind.
1. Super-incentivize snitching. Reward whistle-blowers to the point where it becomes an easy decision. Not only monetary, but with honor and with medals. Make it the new "right thing to do" in public service. Fight corruption. Easy sell.
2. Super-disincentivize ulterior motives and their actions. Treat crimes by officers as far more severe and malicious than of non-officers. And they are. So if a police officer murders a civilian, punishment should be 10x or 100x. Same with stealing a slice of pizza or ignoring a stop sign.
The point isn't that we should punish officers more. The point is we should all raise them to higher standards, and the officers themselves should willingly accept that higher burden of responsibility.
It should be their responsibility to not profile or discriminate based on appearances of anyone or their car. It should be their responsibility to preserve life at all costs, even at a higher risk to themselves.
And this will deter crookedness and incompetence. If an officer cannot do their job, they shouldn't. And if an officer thinks they can get away with anything, they shouldn't. Being a cop or even buying a cop like in the movies should not pose any criminal opportunities.