Well, unlike modding the actual Arduino libraries, it's not out of the question to modify the bootloader that's used on the chips to make them a little "smarter", like adding the lower brownout detection settings to the loader code, eh?
I imagine all the loaders are open source, and they might be assembly, sure, but I think we can jimmy a few additional settings in there early in the code so it has the best chance of catching the "stfugtfo" instruction quick enough...