Instead of using fakeif I'm now using libmacspoof (method #2). Together with libfaketime and the hexeditted file this works like a charm on latest 2.2.8.436 without changing the actual MAC address.

Fixing navicore.desktop is also easy: You can find the location with dpkg -L map open it in text editor. When it says Osso_Service, comment it out. When it says Execute you comment out this line, and you add an Execute entry pointing to your shell script.

Now I can safely & conveniently go on vacation for a week. Phew!!