Since I have owned a nüvi I have always used MapInstall to send maps to the device rather than allowing Garmin's automated software to do the work. But until the maps no longer fit I had always sent the map to internal storage. Once I found the patched MapInstall executables on this site, I changed my routine and sent the maps to the hard drive to be copied to the device by me.

Now that none of the units I have access to can fit the entire map on their internal storage, it's simply a matter of copying to the SD/MicroSD card. In the case of the 1300 I have, the Junction View file goes on internal storage so the space isn't wasted.