Is there a better way to distribute Android alpha versions to testers?

I'm currently using the Android store to distribute alpha versions of my app to testers. It works but the latency is unpredictable and long. Sometimes it's two hours. Sometimes the app won't download till they uninstall it and try reinstalling. Sometimes it becomes available on one device but not another.

I completely understand the need for Google to check for viruses and schedule downloads for production releases. But for a handful of testers? Testers need it now, not tomorrow.

Is there a work around for Google's latency? Is there a better approach?