Maintenance Test Flight Procedures
Tournesol, you are not being too cautious at all.
A thought: while you are in discourse with the manufacturers Production Pilot staff, see if they will get you a copy of their Standard Operating Procedure, which should include the various ways that they control their production test flights. Once again, if you get a few of these documents, you can selectively choose the elements that fit your situation.
A wise thought to create a systemic methodology for conducting these types of flights. It will save you headaches and maybe going to an unnecessary funeral in the future.
John Dixson