To my undertanding, you get about 10,000 IU from less than a half hour of full body sun exposure, so 2,000 IU doesn’t sound particularly problematic.
I know Vitamin C is water soluble, and dosage is to tolerance, meaning if you start having digestive issues, back off the daily intake until you no longer have problems.
Many, many thanks to both of you kind Freepers for the good information.