The battery + boost converter board seems to be working. After a blown out board due to ordering the wrong inductor (note to self: triple-check BOM), things seemed to work pretty well. The boost converter accepts as little as 0.9V from the battery and outputs ~2.8V, the supply voltage required by the imager and therefore the common supply I'll use for all other components.
The proof is in the molten lead pudding:
Fully assembled (with the right inductor this time).
Running at minimum voltage
~2.8-ish volts. Maybe 1% resistors next time.