Tbh, you are better off doing the USB method, as the games that have long load times boot way faster on USB. You can still use it offline, once you have installed the HB channel via Haxchi, as it does not require any internet connection or sig checks patched to work.
My setup offline is:
USB 500gb drive with WUP installed titles inc, latest updates and DLC and Eshop VC titles.
Haxchi HBL+ Official HBL channel (Dimok) since it has more privilages but requires iosuhax fw.img with sig checks.
SD card with Loadiine for titles not compatible/available via WUP install.