A question on assaulting from a vehicle

So, this may be a silly question, but... can you assault OUT of a vehicle? Does it state anywhere in the rules that you cannot launch an assault if the unit is in the vehicle? If not, then what you can do is move your raider up to about 6-8", shoot with your wyches in the shooting phase, and declare your assault in the assault phase. You wont lose any wyches to overwatch unless your ship goes the way of the Hindenburg, and you can charge after your raider takes the overwatch fire...

Seems pretty piratical to me...

Just because it's the way we always did things before, doesnt make it the right way to do things now...

Units may only voluntarily embark or disembark in the movement phase, so no they can't