Glad to see some agreement. Your DAR should be all the radar you need, that actually mimicks night radar of the time well enough. If you are out of your Dot DAR range well you wouldnt know friend from foe (as a RAF Halifax crew said to me, all fighters were NME till they proved otherwise
If you want some way to spot people in pitch black add what they really add, flickering blue exhaust flames, visible only from the rear and only at fairly short range. This was like a gas burner type of flame that pulsed out of the exhausts of the engines, faint but bright enough in a dark sky to show a target if you got behind one. the Book Night Fighter describes this sort of action rather well.