We went on a sand plum picking mission, and saw a few things along the way.
So yeah, the drought has definitely affected production, which I feared. But there are more on the bushes that are not ripe yet, so we'll go back in a week or 2 and see how many more we can get. If I can't get enough to do anything with this year, I'll freeze the juice and add it to next year's haul - assuming that there is one.
If anyone local knows where I can find any more, let me know - I'm willing to split the harvest if we can get some more!