v10.2.4 - install base config on an inactive volume, leaving other volumes intact

I am testing my disaster recovery process on a 1600 GTM running 10.2.4HF3. My intent is to load the base config on an inactive volume on a lab unit, boot to that volume, and restore the config from a prod unit, leaving the initial active unit alone so I can boot back to it when I am done.

The command I used in the past to do this is:

image2disk --force --nosaveconfig --nvlicenseok --instslot=(inactive_volume) (path_to_iso)

I think this stopped working after I upgraded from 10.2.2 to 10.2.4, but I'm not positive on that. When I execute this command, the install process was reports as successful but the software version never actually changes and the config from the active volume is pulled ahead.

Today I stumbled across "SOL10519: Restoring the BIG-IP configuration to factory default settings (10.x)", which states this:

Note: Beginning in BIG-IP version 10.2.1, when the image2disk utility is used with the option --format , the utility will always install the software to the first available boot location after formatting the file system, hence it does not required to specify a target install location.

So I ran this command instead:

image2disk --nosaveconfig --format=volumes 

Uh, this command did definitely work in the sense that the base config was loaded, but ALL of the volumes were formatted - not just the "first available boot location". That sucks.

Is there a way to format an inactive volume and load the base config, leaving the active volume intact in v10.2.4? The doc on software and volume managent is very confusing.