How to install certificates in production?

I would like to flash certificates in production.

My plan is

First, flash an app for installing parameter like client id using nvs and certificates.

Then, flash a production app. This app reads the parameters and operates mqtt using the client ID and certificates

When I install aws_fota app, this warning is displayed. So it's not good idea to use provision_certificates function.

#warning Not for prodcution use. This should only be used once to provisioning the certificates please deselect the provision certificates configuration and compile again.

Also, this link recommends to use LTE Link monitor, but I guess mistakes easily occur in copying and pasting certificates.

Another option is to use AT%CMNG by at_cmd.c, but I'm not sure this can avoid the above security risk.

Which option is suitable for production? 

Thank you.