External = root dir GAMEZ
Internal = dev_hdd0/GAME/LAUN12345/GAMEZ
If you set your directories up like this and install your managers via thumb drive the managers will always install to dev_hdd0/GAME and will be no where near your internal game directories and you can install and uninstall all you want.
Set the LAUN12345/GAMEZ up via FTP before you install the managers and it will ask you if you want to use this folder, at least all the new managers do if it's already there. If you install your managers first the manager may ask to set up a different folder which may be problematic when using more than 1 manager. At least the older versions of Gaia wanted to use OPMAN12345 or something like that.
Having more than 1 manager installed is a good way to go since not all games run the same under all managers. The same holds true for payloads; what runs great with one may not even start with another.