Do gradle plugin portal releases to bintray instead of directly to gradle plugin portal.
The gradle plugin portal's directly upload mechanism doesn't seem to support tracking download which we require : https://discuss.gradle.org/t/plugin-portal-download-statistics/11609/5
But there are mechanisms for publishing to the gradle-plugin portal via bintray instead which does give all that information : https://bintray.com/package/readme/etienne/gradle-plugins/gradle-plugindev-plugin
I would do a little poking around, I haven't done all the homework on this yet.
Can't seem to find method for using Bintray as the hosting repository for a Gradle Plugin Portal plugin - posted a question about it.
Linking an existing Bintray repo seems to be just copying the the artifacts to plugins.gradle.org/m2.