Thanks for your replies.
I am looking for the promoted tweets (not promotable). Specifically, I am trying to retrieve the Tweet ID, Line Item ID and the Tweet Text. If using the REST API causes issues with rate limits, I may be able to get the tweet text by calling Tweet.preview for each promoted tweet and parsing out the appropriate section of the HTML. But this seems like a very roundabout way to get it.
Also, I am using the Python SDK (v1) but I do not see the Promoted Tweet endpoint (accounts/:account_id/promoted_tweets) in the Account class. I have added my own but should I be using another?