AFAIK there's no way to do this with a custom filter. What I would do is to use the filters in the top list to get fewer results and then add those to the virtual GPS (or virtual GPSes as you'll max out the list).
For example, for Yorkshire you're adding the top 1341 if you're doing it today. For West Midlands you're adding the top 1298 and so on. For most areas it will be enough to just do them region by region. If a region has more than 10k you can get creative with Hidden date, D/T or cache type. For example first checking all traditional caches in the area and then checking all other cache types together to hopefully get to less than 10k in each search.