Fwiw, my impression of the suspension is that there's nothing a few small springs slid inside the shocks couldn't handle (the kit actually comes with stops to put in them if you want to freeze the stance). The kit's problem is that it relies on the springing force of the plastic torsion bars, and of course, the finished model is way too massive for that, as has been adroitly pointed out a few times here already. I'd also second the notion that using some metal rod stock to replace the plastic pins in various hinges will be quite helpful.
I was rather distressed about the warpage in my tires too, but it seems that Trumpeter might have developed a concept to address that - simply trim some foam rings to fit inside as a kind of inner tube.