Include a CKEditor Plugin in an Install Profile / Distribution

Question

I am working on an install profile that needs some CKEditor plugins. For example. the template plugin. You can add the module no problem:

composer require drupal/wysiwyg_templates

Getting the JS plugin seems to be a bit harder. There seem to be 3 options:

1. Using composer:

{
    "repositories": [
        {
            "type": "composer",
            "url": "https://packages.drupal.org/8"
        },
        {
            "type": "package",
            "package": {
                "name": "ckeditor/templates",
                "type": "drupal-library",
                "version": "4.5.7",
                "dist": {
                    "type": "zip",
                    "url": "http://download.ckeditor.com/templates/releases/templates_4.5.7.zip",
                    "reference": "master"
                }
            }
        }
    ]
}

2. Using a manual install:

Download a tarball from the CKEditor site and unpack it into the web/sites/libraries directory.

3. Ship plugins within the codebase:

Drupal core ships with some libraries in its codebase, are distributions allowed to do that too? (In this case, CKEditor plugins are GPL code.)

---

The problem with approach 1 is that all projects based on your distribution need to have that in their composer.json file too. If you wanted a couple of plugins, you how have to include an extra 12-or-so lines in every composer.json that uses your project. If you wish to add a new library you break all existing projects.

The problem with approach 2 is that you're adding a manual setup step in addition to composer install. Very undesirable.

The problem with approach 3 is that it might not be allowed, and you might have trouble getting contrib modules to find these libraries based on the install location in vendor. Still, it seems like the only option that might allow you to work around the boilerplate and manual download/update issues.

If there are any examples of a distribution handling this nicely that would be appreciated.