Yea, the physics are on nobody's side, I'm afraid. We've gone through several iterations on design that kept changing the scope, and the code base reflects that in its utter horror. So making any substantial changes got more and more difficult as things went on. I spent most of my time just trying to figure out what Unity is actually doing in the background, because the documentation is rather... silent on the matter. Only through a last minute discovery did the core gameplay even work out, but it introduced some new instability. Either way, with some cleaner code and a better approach I think this kind of thing could actually be pulled off, which is quite neat. Though one might be better off just writing the physics side of it themselves, these big physics engines are just too jittery and there is very little one can really do about it :(
Thanks for the comment!