What would be the risks of modifying the original SD card contents? It came with the "lock" switch on, and I really don't want to end up with a "dead" unit. Maybe exploring all the options using a copy would be the safest ?
I'll try to find a way to get the SD Card ID using one of Neil's suggestions.
Thanks to all, I REALLY appreciate all your help and suggestions, and am willing to explore all of them :)
If modifying the original card's content is safe, would it be easier to have a new version of the map and then change it so that its name, unlock code and everything is the same as the factory installed one, and just replace that img file, leaving the unl and everything else intact?