Support for a single mcuboot application slot

I have a board with an RA4M2 chip in that I would like to use MCUBoot for, however I would like to be able to configure MCUboot to support only a single bank for the firmware upgrade process rather than the regular 2 that the Renesas Configuration editor seems to enforce, to allow larger images.

I've looked into the MCUBoot options and created a custom mcuboot config file(that I've set within the mcuboot properties) however that toggle doesn't seem to have any effect (CONFIG_SINGLE_APPLICATION_SLOT).

Is there a way to configure MCUBoot to only support a single image bank for the RA4M2 chip?