High Efficiency low power Charge Pump

I have a design using a single Li-Primary battery and I am trying to optimize my power system. I have used charge pumps in the past but but this time I am aiming for maximum battery life possible. I only need 50uW static and 175uW dynamic to run my display at 5 vdc everything else will run at battery voltage. I have looked up a couple charge pumps but almost all of them massively drop efficiency at these power levels. Does anyone have a recommendation? Or can they point me in the right direction?

More data on whats needed:

The 5 vdc power rail only covers the LS027B7DH01 analog and logic power (4.8-5.5 vdc).

Thanks in advance.