I've provisioned a handful of CAPsMAN setups but they've always had the cAP ac connected with PoE wired connections. I know when you put a device into CAPS mode, it basically configures it as a switch with the Wi-Fi interfaces getting their configuration from CAPsMAN.

However, can you uses CAPsMAN where the uplink is via wireless? I know how to manually configure a Router OS device as a wireless repeater but I suspect it's not possible with CAPsMAN as it takes over the interfaces entirely.

You can specify which interfaces participate in capsman and which are excluded.
It's not all or nothing.
You enable CAPS mode on your AP but still you need to specify per wifi interface which one will be manager: capsman, local or capsman-or-local.

Reset to CAPS mode is just a simplification of config to put everything on bridge and add all wireless interfaces under capsman control.
But you can always change that.

Suspected as much. Would be a nice to have as mesh set-up is sometimes a requirement.