I really do like your suggestion, but my results have been limited. In "unique count of hostname" + "as single value" shows 7448, and this is over the last 7 days of data.
I reset, and I try "unique count of hostname" + "over time grouped by hostname", time grouping 1 week and the chart type is a table. I export the Chart Data, and I only receive an export of 2K lines.
Do you know a way around this limitation?