Go to the automotive department in a store like Target or Walmart. There ionizers/deodorizers that plug into the light socket, some are just big enough to plug in, very small size. Saw them about a month ago, while looking for some glue to re-attach my rear-view mirror, the dog knock off.
Oh, should mention a neat little trick I came up with, worked well. Before scraping off the old glue from the windshield, I outlined the placement from outside with a Sharpie. The metal slug on the mount slips out, and is magnetic, so used a strong magnet (from a Hard Drive) on the outside of the glass to hold the slug in place. Seems like it's going to hold, done a few over the years, doesn't always hold up well.