1. your test node hostname assumed as my_hostname.my.domain

2. use dev.pp for my_hostname.my.domain declaration
├── manifests
│   └── clusters
│       └── dev.pp

3. use hieradata/region/staging.json for parameters and data
├── hieradata
│   └── region
│       └── staging.json

or use more specific place
├── hieradata
│   └── node
│       └── my_hostname.my.domain.json

4. update aliases if you want to get root emails
└── modules
    └── wg
        ├── files
        │   ├── etc.aliases

5. update or create anything you want - it's going to override files from puppet-dev

6. put overrides into puppet-dev/overrides directory