Longtime here but my account got corrupted/deleted (so I apologize I can't post direct links yet) but I discovered a way to run loadiine games off of a usb hard drive formatted in fat 32. I doubt i'm the only one that noticed this, but perhaps no one has bothered to make a tutorial before. Might help a few people, or people with specific requirements for their setup.

Before we start here are the pro's and cons of this method:

PRO:
*Hard Drive can be fat32 format
*Hard Drive not limited to ONE wii U
*Faster transfers from computer directly then having to ftp it or rip it to drive.
*doesn't require more then one channel install on the vwii (outside of hacking it).
*can connect the hard drive direct to pc for file copying
*can share a hard drive with wii regular if you need to rip your wii/gamecube (older wiis) games to it.

CON:
*Hard Crashes on reboot, or app exit. (have to power it it off manually)
*any of Mocha-fat32 instability while loaded.
*Requires the install of one channel on the vwii
*only works with said channel forwarder so far and requires 1 of only 2 versions of special loadiine elf
*slow load times

Trick: Basically found out that if you load mocha-fat32 then use the loadiine-channel forwarder (not the app in homebrew) it will load the contents of your fat32 hard drive into loadiine when installed correctly.

Instructions:

Refers heavily to the Offical [RELEASE] Loadiine Forwarder Channel by brienj here on gbatemp.
Billy Acuña made a version of the Loadiine y1 mod that works with the forwarder as well. linked in the first post.

First go to that thread and download the file from Download link -
Alternately download the second link if you want the loadiine y mod comptabile version.

Install the channel onto the wiiu menu.

copy only one of those two compatible elf into sd:/wiiu/apps/loadiine_gx2/loadiine_gx2.elf

Install mocha-fat32 from homebrew store or manually on sdcard in wiiu/apps subfolder

connect your fat32 hard drive/usb stick to wiiu via usb with some games formatted to run in loadliine, the drive must be fat32 and mbr and <= 2tb in size, also cluster size of 32k is generally standard. Formatting or (erasing the drive clean) is needed if you don't have one lying about yet. You'll need to download guiformat tool for Windows otherwise it will try to format bigger hard drives in extfat (aka fat64) which is not readable on a wiiu, or much of anything.

boot up wiiu and launch haxchi exploit or if you are are using coldboot you can launch mocha-fat32 directly (not autoboot tho!!), if it is path renamed to sd://wiiu/apps/mocha cbhc load it vs what the homebrew store says is sd://wiiu/apps/mocha-fat32, after launching mocha-fat32 launch the loadliine channel forwarder, it will load but take a while, if you here sound clicks on the tv or pad its loading a lot of games.

After you load a working game you will need to hard power it off to quit when you are done.

*You don't need mocha-fat32 for others uses, like ftp still reads fat32, that I've found or for vwii to read usb fat32 drives. so power it off when you are done using loadline and don't make it autoboot or you'll face freezes if switching to too many apps on wiiu homescreen or homebrew menu.

that's it. Hope it helps, sorry i'm late to the loadliine party but I've been doing this for quite some time, I didn't fathom that no one else didn't notice this trick.