Realistic? I'm not so sure.
Since when is the lightbars purpose to warn people either ONLY infront of the police vehicle or ONLY behind it? I believe laws say the emergency lightning MUST be visible from ALL angles of the vehicle at all times.
Indicators and parking lights in the lightbar? Tell me a lightbar with that feature, even If there is a lightbar with that feature, I don't see the need for It.
Sorry, but I don't know what reality you live in.