Decide with the product and legal owners which specifications, architecture notes, and test records can go into the file, and prepare redacted versions where needed. Descriptions written for the purpose often work better than raw internal documents, provided they are accurate and someone with direct knowledge can attest to them.
Plan the redaction before the deadline
Confidentiality review is slow when it starts late and competes with launch work. Identify the approver early, give them a short list rather than a folder, and record what was withheld and why so the file reads as considered rather than thin. Where material cannot be shared, replace it with a dated statement from someone who can describe the work.
Keep versions labelled so a later reader knows which build each document describes. Decide in advance what the file will say about material that cannot be produced. A statement recording that a document exists, who holds it, and why it is being withheld reads very differently from silence in the same place.
Where a redacted version is possible, say what was removed and on what basis. Keep the confidentiality approver's own decision in writing too, so a later reader sees a governed process rather than one individual's judgement call. Hypothetical example: a hull coating systems specialist's strongest evidence is a formulation record that cannot leave the company, and the file carries a dated statement from the technical director describing the record's existence, scope and restriction, in place of an unexplained gap that a reviewer would have to interpret alone.