1/5 the daily power requirement is surprisingly decent. Swapping out the screen for an eink display or ultra low power LCD like those from PixelQi and downclocking the SoC might be enough to make up that gap.
FYI, your comment made me look up PixelQi and Wikipedia says that conpany died almost a decade ago (although 2015 feels to me like much, much less than a decade ago):
> "By 2015, PixelQi's team and offices were unreachable, and the company is presumed defunct.[3] The intellectual property is now owned by the original investor of Pixel Qi, while the right to manufacture Pixel Qi technology contractually rests with Tripuso Display Solutions.[4][5]"
