I don't know if the demo and the full game share the same ID, but I reallized that the romfs is basically the "full" game rom.
I have two ideas:
1.- Dumping the romfs from the cia full game and run it with the demo via Hans.
2.- Dumping the romfs from both (demo and full game), decrypt both of the romfs files, merge the full game romfs with the demo romfs, encrypt the "patched" romfs, rename the romfs with "(demo id).romfs and finally run it with the intalled demo on Hans.
I have two ideas:
1.- Dumping the romfs from the cia full game and run it with the demo via Hans.
2.- Dumping the romfs from both (demo and full game), decrypt both of the romfs files, merge the full game romfs with the demo romfs, encrypt the "patched" romfs, rename the romfs with "(demo id).romfs and finally run it with the intalled demo on Hans.