Mocha with FAT32 support has been compiled here:
https://gbatemp.net/threads/mocha-cfw-the-sweet-chocolate-to-your-latte.452940/page-45#post-7086884
With this (BETA !) version, you can use your USB FAT32 as if it was your SD card.
so imagine you have a 2TB SD Card, no more space issue to install a game to NAND using WUP Installer
just don't use WUP installer to install to USB FAT32 partition, it's not working yet.
run Mocha, then every SD access will be done from USB instead. (it's not a feature, it's a bug, so get advantage of that bug for your SD space issue )
all homebrew trying to access SD will in fact see the USB First primary partition (no GPT !)
How about using WUPinstaller to install games to SD card (either formated as FAT32 or as Wii U format if such thing is possible ?) ?
I wish I could recycle my 128GB SD card to install games to it without using Loadiine... I can use 32 GB of it if I use RedNand but that's all...