My mate had one working whilst moving, but was a pain in the ass.
If i remember rightly got a cheap ALBA Freeview box, ran the RF Sensor from the boot to the front of the car. He than got a omni-directional ariel put that on the parcel shelf than further more had another aerial that came in the box on his roof with a booster in the boot of his car.
Was a royal pain in the ass if i remember rightly, but still would scramble in certain area's and when you left that coverage area for the main reception.
Omni-directional aerial would help plus a seperate booster.