Automatically send the customer a link to download their invoice when the order ships.

I want to automatically send an invoice along with our email template once an order has been shipped. Right now, I have the automation set up to send our email template plus the link to download the invoice after the order has been shipped. The issue is that the invoice download link (which appears in the email template as [[ShipmentLink]] is labeled as a box label and not an invoice. Apparently, it is not possible to have the customer-facing text associated with [[ShipmentLink]] be anything other than "Download Box Label".

Trying to set it up as a workflow doesn't seem possible because the other placeholders we use like [[Carrier]] and [[TrackingNumber]] aren't supported in the workflow section. 

The ideal solution would be if the [[InvoiceLink]] parameter was available in the Automations>Notifications>Sale>Sale has been shipped section but sadly it isn't. I really hope this gets added ASAP.