To close the loop on this, the campaign ID system token ({{campaign.ID}}) has the information that I need to automatically append tracking info to links.
Here is an article that lists many (but not all) of the system tokens that are available:
https://community.marketo.com/MarketoArticle?id=kA050000000LBvaCAG
Note the article above doesn't include campaign.ID but that is indeed an available token.
Hope this helps someone.