Features versus Configuration Management
I would advise using Features. This would allow not only exporting functionality and compartmentalizing it a lot easier, but you could also have the ability to bring in features later from an external source, and/or, use certain features here on a different site that didnt start with your installation profile.

Currently there is an issue to support custom path generation for Features:  https://www.drupal.org/node/2693123

When that is addressed, you can generate the features to the path of your choice. For now, you can generate the result, grab it out of modules/custom and place the generated feature module into your profile.