Hi @JFeighery,
Thank you for this information and glad that you asked the Community!
First, I’d like to share this documentation “Line items” that might be of interest.
I have found a similar post about this subject from @IsaacTakushi “Getting Line Item Product type and term data” that might help you.
Also, the solution from @MichaelC on this post “How to create, update, or read the “Start Date” for a Line Item object?” might be of interest.
I also wanted to invite a couple of subject matter experts to this conversation: Hi @himanshurauthan, @JBeatty and @HFisher7 do you have suggestions to help @JFeighery, please?
If anybody else has anything to add and/or share, please feel free to join in the conversation 
Thank you so much 
and have a great day!
Best,
Bérangère