I would recommend using DIVA for Grasshopper's "Illuminance" component and setting the specific date and time in the "Sky" component. This will allow you to run the analysis just for a given hour. Since you only have 9 hours to simulate, this should be relatively quick. If you need to simulate the sky based off of the climate file, you can select that option in the "Type" pull down. However, for CHPS compliance, I would suspect that they may set a certain sky condition under which to model? If its a clear sky, then that option is also available and the "Illuminance" workflow and the proposed workflow is preferred instead of using"Annual Daylight" since "Annual Daylight" will use the climate file, which will have inconsistent sky conditions across your critical dates and hours.