Variables used in home dashboard

I am using variables in many of my dashboards to filter down to a specific set of hosts in an AWS Cloudwatch data source. This is working well, I just include “var-host_prod=All” in the link to the dashboard. An example variable definition looks like:

Now, I want to add some similar filters to panels in my home dashboard. Since this is landed upon without clicking on any links, I don’t see a way to preset the variable’s “all” parameter. There doesn’t seem to be a way to set a default value on the variable definition page.

Any ideas?