Bryan,
I was thinking for a while on how to improve knife edge flight and came up with an idea similar to yours, but maybe not quite as simple. I have a feeling that your strake in front of the fin may be acting like a simple 'winglet'. If you look at this CFD image from Alex Voicu's thread - http://www.rcuniverse.com/forum/m_89..._2/key_/tm.htm (hope he doesn't mind me using it) you can see that the higher pressure air under the fuselage is leaking around the top of the fuselage and is being wasted. As the tops and bottoms of fuselages are usually nice and rounded, that helps the air to leak nicely from on side to the other in a sideslip (such as knife edge). Adding a simple strake like that could (in theory I suppose) help improve the fuselages 'lifting' efficiency?
But then again, it would probably amplify the effect of a cross wind?