Well, have you tried adjusting the sliders so that they have a wider flat low area in the middle? That way you'd have to move your head more to enguage those axes. They wouldn't affect your gunnery but when you move your head to start looking back they would come into play. You might have to have the curves rise fairly sharply after the "deadband" area you've created, but I don't see any reason why it shouldn't work.
Also, after a bit you should start to get a feel for the nose of the plane and convergance point and find that you really don't need the sight anymore. It took me a couple of months to get comfortable shooting with trackir (which is saying something as I've only been on ah for 7 months) but I did get adjusted and it's not a problem anymore at all.
Just my .02. I still do a bit of tweaking on my profile now and then, but I like it quite a bit. Just try making one small change at a time and give yourself a few days to get used to it, then change again till you get what you're looking for.