Best for spring wrap??

I'm making my own rear packs, and hope to be installing a 4.7L stroker next year. I want to build my packs (only 2", for a camping/light off road vehicle) so that they can handle the torque of the 4.7 and still flex well. I have done a search on this, and the BEST plan seems to be to do a traction bar.... But I don't weld.

So, what is a better plan fora good combination of daily driving and flex? Use a factory second leaf on top of the main leaf, like they did here http://www.jpmagazine.com/howto/16719/, or use a stiff overload leaf from a Dakota spring pack?

Thanks,
Geoff