I am running saddle packs - so I guess a lot less stresses involved. My pack does move around a bit in the car, do you find the same? I've not actually installed any foam though. I wonder is some sort of carbon fibre battery strap could solve your problem by stiffening things up a little bit?
I can't really see the chassis flexing enough to cause this - maybe it is, but I just can't see it. There ARE chassis' about that flex that much, but surely not the durga?
