How to insert a message of 20 mb into Azure Cosmos DB - Document DB API

Question

We have a requirement for our application to handle incoming message requests of up to 20 MB in a transaction. This message is well structured and has nested objects and arrays. We are planning to use Azure Cosmos DB (Document DB API) as our database. As Document DB has a limitation of 2 MB as the maximum document size, we have modeled our message data to be stored in several document. We were trying to insert all these documents in a transaction using the Javascript Store Procedure, but the SPs have a size limit (2 MB) on the request size.

Can anyone help us with how we can save all the documents related to the 20 MB message in a transaction (save all or none)?

One way I have come across is to save the documents independently, and write a store procedure to identify and delete them all in case one of the write fails. I'd like to know if this is the best available approach for our scenario.

Edit: Another possible approach I was thinking about - Upload the 20 MB message into a blob storage, and access it from inside the SP to split and insert. But I couldn't find a way to access the blob from the javascript SP (XMLHttpRequest was not allowed in the SP)