Killabeez, my thoughts on your line...
4 ... Bg4 seems very playable and relatively equally, e.g. ... Bg4 5. dxc5 e6 6. h3 Bxf3 7. Qxf3 Bxc5 and Black is pretty even, or so it looks like.
As for your line, 10. Nb5?! falls to Nd3+ 11. Qxd3 Qxf4 where you are probably worse for the experience. Better is 10. Qd4! f6 11. Nbd5 where you get at least your pawn back and a solid lead in development and overall structure.
Nice idea, but if they don't accept the gambit with the simple 4 ... Bg4, I feel like Black is better than if you had just played any one of the more standard lines.
That's indeed a nice trap that I could not trace back to a book on the CK.
Thanks. It isn't in any books because I created it.