SiDi, there is no reason to think that she passed through the death stage before turning into salt. Not that it would matter if she did, though.
As a side point, I don’t think a ‘rationalist’ would have such a hard time with this. The whole turning over of Sodom and Amora could have been a natural occurance. Chazal do tell us that the area was volcanic, and the Passuk describes the area being washed out with sulfur and salt (not necessarily table salt).
Hashem doesn’t need Nisim to run his world. Contrary to the common attitude that Hashem’s intervention has to be in the form of a bolt of lightning, it doesn’t. The pasuk says, Ha’aretz Hadom Ragli. Hashem runs all the variables, and there are more variables than we normally realize.