I don't know if this is the best way, but I did figure out how to change it for this game and disable RetroArch saves to eliminate accidental overwriting. In case anyone else needs this in the future:
Create config file based on instructions from here, name will be [ROM NAME with Extension].cfg
In that file paste the following with the hotkey button of your choice:
#Change Hotkey for this game only
input_enable_hotkey_btn = 3
#Disable RetroArch saves
input_save_state_btn = null
input_load_state_btn = null
# Never save-on-exit after an override config
# or the override will make into the core config.
config_save_on_exit = false
