I have faced about the same problem. I use hashes that look like this...

$inf = {
  test => {
    host1 => {
      app => {
        setting1 => 'foo',
        setting2 => 'bar',
      },
    },
    host2 => {
      app => {
        setting1 => 'baz',
        setting2 => 'buz',
      },
    },
  },
  dev => {
    host3 => {
      app => {
        setting1 => 'a',
        setting2 => 'b',
      },
    },
    host4 => {
      app => {
        setting1 => 'c',
        setting2 => 'd',
      },
    },
  },
};
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My perl scripts typically end up rewriting configuration files based on environment/host, using the hash to drive the rewrites. I take this approach because I use a system like this to configure large numbers of COTS products along with proprietary software for a large number of environments and hosts.