Hi Eric,
Good to hear from you and thanks for the update! Sounds like you're making great progress!
The ADS1248 is a great option and would bring your power consumption down significantly! One thing to be aware of is the required external capacitive load needed with the internal reference. This reference capacitor increases the reference settling time.
Another great option may be the ADS1220. It's power consumption is comparable to the ADS1248, but would allow you to turn it off and wake it up quickly. It's internal reference does not require an external capacitive load. Therefore, the internal reference settles within the 50us that is also needed for the internal oscillator to settle. The ADS1220 also holds the register settings in power-down mode.
Best Regards,
Chris