Hey Calamity - I have a R4 SDHC Ultra with the _SYSTEM_ structure and seeing retrogamefan's work has me intrigued. I believe this card is not dstt based though... as I got AKAIO from the website r4ultra.com and have it working playing newest games...
Still I'd be willing to help test - I tried...
btw i feel this a good time to remind you guys that sea of thieves was made by rare, who also made DKC1-3 and DK64, alongside banjo kazooie and conker's bad fur day