Budget for once per month on 1. And the same frequency for 2.

There are other uplinks that maybe a rotating check could be snuck into I guess. Like 1 bytes of index, and 1 byte of data and have it cycle through. But I need an instant yes/no response without wasting energy or bandwidth.

Battery powered radio transceiver to wall powered radio transceiver
Conceptually think "weak cell phone with wimpy battery transmits to high power cell tower"