Tiks goes here:
/vol/system/rights/ticket/apps/
But not sure if tickets are decrypted on installation.
WUP installer only rewrite the /nand/install/ folder path to sd/install/ folder path, and trigger the official installation fonction.
the console look in the new path, sees app/h3/tik files so it decides to install the content to the user selected location.
Like you noted, the ticket is installed (copied) into /vol/system/rights/ticket/apps/
you could try to install a game to USB by extracting and copying the game manually (JnusTool with extracted option, or wud decrypters, app decrypters, etc.) with your computer's file explorer.
then, manually copy the ticket to the NAND.
see if it's detected as installed !
On Wii, the ticket file alone wasn't enough, you had to edit another file to register the ticket as bought. maybe WiiU has the same kind of file that you need to edit, or maybe not. I think nobody tried !
it might have something to do with "tik2sd", that program can tell you which TitleID is linked to each ticket. I don't know if tik2sd just parse each ticket to find the titleID or if there's another file involved. would have to look at the sources.
Both drives plugged in at once should work though, as long as the Wii/GC drive is hidden with uStealth and is the first drive (top rear port), no?
Yes, and no.
the plugged order would be important, as vWii cIOS mount USBPort in incrementing order and vWii IOS58 mount USBPort in reverse order. When using nintendont it would try to mount the WiiU HDD if it's plugged in a higher port.
users are having issues when they don't understand how to plug 2 or 3 drives at the same time to get everything working correctly.
there's a way, but it's always specific, and it's hard to always re-think about it. I should make it public, people always come to ask me in PM, I'm tired of PMing useful info 50 times instead of making it public once.