i think sony disabled recognizing anything that would let you install etc. from usb or even leech the pkg via webbrowser.
and its prolly not related to the dir structure/flags or anything. the psp eboot.bin decrypter is from what i read just a 'dumper' as for decrypting you would need to know the keys.
and the way about dumpin bd game to hdd... that's what some ppl with their test/debug consoles do here... tho they're using the debug packages (updates)
but maybe your idea would work... tho psn games usually need to be activated...