Finally did the update and wanted to let everyone know the process I went through. I extracted all three ISO's to a 32GB flash drive. There were no file conflicts when consolidating each disc into the pkgdb directory, the config.nfm file is the same on all three discs so you can just copy one from any of the ISO files.
During the updated the system showed (USB 1/3) the entire time but didn't ask for the next USB drive and copied over the entire NAV update at once. It took just under 45m for the entire process. After it completed however the system prompted for (USB 2/3) and then (USB 3/3). I had to create USB disks 2 and 3 to finish the update. All it did was quickly read each disk, it took under 10s. So if you're looking for a way to update your NAV without popping USB flash drives in and out while on the road this method works, albeit you still need the last two disks to get it to complete the process.
I also can vouch for Sergej. Great communication and I received my FSC code from him within 5m.