Hello, I am curious if there has been a solution to this issue.
When building a theme, you can change the display conditions to identify and work for specific CPTs. By setting a specific custom post as the preview, you can draw in the dynamic tags from that post for which to build.
Lee is correct, CPTs should be available to access through both Preview Settings and Template Conditions.
When using Pods, this isn't an issue. It is for Meta Box.