I will use a pre-filled container that will hold ~3 days worth of RO water. I have the 300g tote for RO, so pumping over ~30g twice a week wont be an issue. Also, filling directly from an endless supply of RO water terrifies me... switches stick/solenoid sticks/ etc. I don't mind using a sacrificial $8 8gph pump.
I have a full-time job, and am a single parent of two toddlers... so automation, simplicity, and fail-safes are all important.
I had a controls-logic diagram on my desk this morning for how to do it (my coworkers rock!) Basically (if im understanding it correctly) you have the bottom one NO, and flipped upside down. The top float is NC, and right-side up.
The way it works, is if the level goes below the lower float, the pump turns on, and latches. Once the water level goes above the top switch, it shuts the pump off. The "latching" action is what will allow the bottom float to bounce without the pump chattering.
@Overgrown: I'm hoping that the laminar airflow through the garage will provide enough air exchange to keep humidity in check. I'm monitoring %RH, and there is no significant difference (so far) between outside and in. IIRC the red-line is 80% RH, which is (unfortunately) a normal day in the swamp.
I'll look into the Santa Fe Impact. I can see that being particularly useful for the few days that it does get cold, and the garage gets sealed (and the heaters possibly turn on

)