You can have ill effects from too much Vitamin D. However, the same applies to water.
From what I’ve read, the upper limit on a consistent daily dosage before there’s a danger is 10,000 IU. I know people who take 50,000 each 2 weeks (plus, of course, what they get in their diet, which amounts to a few hundred a day), but if you average that out it is under 3,500 IU/day.
I, personally, wouldn’t take more than 5,000/day unless a doc told me to do so. What you take, or how much you receive via the Sun, in any one particular day, or even week, is of fairly low significance. You should be in absolutely no danger at 2,000 IU/day (though, of course, I’m not only not a doctor, I’m not your doctor, so this isn’t medical advice, yada, yada, yada) - and I take that much myself and have for a couple years. No ill effects, just less sickness (despite my horrid sleep habits, which by all rights ought to run down my immune system).
Thank you so much for your very helpful input on this. I think I’ll go with 2000 IU/daily and see what happens. I take a small supplement and try to sit for at least 15 minutes in the direct sunlight everyday, but I can see how that is just a drop in the proverbial bucket.