Drawing heavy inspiration from Matthias Fechner's work on the GitLab port and deployment instructions, I took the approach of deploying PosgtreSQL & Redis services into standalone Bastille jails for each, and GitLab & Nginx services into their own compound Bastille jail, copying configuration files into each as appropriate and rendering them at jail deployment time, plus utility scripts (e.g. post-install, post-upgrade, service status, backup, etc.) for each jail as well.
Everything communicates over a private network, and critical data directories are mounted into each jail as necessary, e.g. Gitlab's repository directory, backup directories, etc.
As a result, all deployment recipes and configurations are abstract and versioned in Git, and deployment, backups, and all other operations (such as log rotation) are automated. If anyone is interested in discussing this setup, feel free to hit me up!
