Hi Tony,
If you slide the taper down, it is still the same total taper. As you thin the limb stack, the taper will still be .002(I think you use).
Maybe I'm not understanding you properly tho...
One way to get tip stability is use a tip wedge,of course this changes the way the tip unrolls.
Wider limbs farther out will help also, but I personally don't like the look...
Going from .002 total to .004 will make the tips even floppier I'm thinkin... And the limb won't bend as much at the fade or wedge.
Want me to grind some thinner glass to get the thickness down?
Just a few ideas thrown out there, I'm not much of a curve builder, maybe someone else will have something for ya!