Why do you need to rename the file? Copy the file to a computer or to dropbox and then run recover to see if FM can repair the database then Import the data into a non-damaged backup. If you don't need any of the data, then delete the file from the device and transfer a new non damage backup to the device.
Just to clarify - the user is out in the field with no access to a computer (just their iPad as that's all they need for their job). The file is too large to upload to Dropbox via 3G/4G - we do need to keep the file so renaming it would be the simplest option.
without a desktop version, I'm afraid that there is no way (with a non- jailbraked device)
You could send an empty, renamed version of the db to that person by email. If that user has an app like 'GoodReader' (pdf utility), heshe can have FileMaker to open the file in GoodReader (from the FileMaker Go start, select the file, use the 'export' icon -> open in...)
GoodReader will not open a FileMaker file - but one can rename the file and let GoodReader to 'open with...'
Although, renaming will not change the structure - but it's worth a try. If the file opens, one can delete some records. If data gots corrupted, it should be working again