You could just have them put the switch on a desk somewhere power it up and disable all the ports, then save the running config, this is a quick change, then rack the switch and cutover as needed and then enable the ports as needed?
I considered that option but I don't think these switches can be powered up outside the chassis. I also verified there isn't an available staging environment where they might perform this prep.
It is probably to invest some time writing a basic script to set the failback to No, that would be your best option. Disabling all ports on the switches is not really feasible option, and I doubt the network agree to this as they will need to basic connectivity when the switches is installed.