One possibility that comes to mind would be to utilize one WP installation to serve multiple domains. This can be done with some code in wp-config.php that dynamically sets the WP site and home URL values. The theme templates would alter what they output based on the requested domain. For example, a different site logo is output for each domain. Unique key phrases can be dynamically inserted into post content by way of shortcodes or custom blocks, similar to how word processor mail merge works.
This way, should you want to change the common “boilerplate” data, it only needs to be done in one place instead of on multiple sites. Meta data, depending on how extensive it is, could be stored separately under keys uniquely defined for each site, or together under a single key as an array of data, or if meta data is extensive, a custom table with a different column for each site.
This is going to require more up front coding effort, but it’ll pay back into the future by giving you a more maintainable, efficient, scalable site in the long run.
