Well, here's another one: I'd do all the other things you've been advised, the this: I'm preparing to start a Mk. IId with a bunch of AM stuff added to the 1/48 basic Hasegawa kit. But while researching my colors, since I've built the kit you're working on (didn't like having flat PE parts in place of very noticeable turbular framing in the fuselage, so I replaced those parts with styrene rod, using the PE parts for a pattern). Anyway, I was looking over Scale Aircraft Modelling Magazine's new series of books, specifically two volumes, Combat Colours (Vol. 2 is the Hurricane) and Camouflage and Markings No. 2 -- The Battle For Britain. These books contain literally hundreds of profiles of planes, and describes the markings in detail.
The Hurricane Night Fighter, as well as other night fighters and the bottoms of lots of aircraft early in the war, was usually painted the the British color Night. This color is not simply flat black. It is a flat black with very dark grayish blue added to it. This would be equivalent to U.S. Sea Blue. So I would add that, and if you are fading the a/c a little so it won't be so black, I would add more of the blue. Not to get a blue airplane, but to get the effect. I think you'll be happy with it.
Tom