Yeaaaaaah finally !!
Got the bike yesterday, with again a whole lotta drama... Short story : they still didn't have the plates, told me to come back on Monday, I said no way.
Pushed one of them on the bike (without plates), went to the Hami lu police station (where I passed the physical, close to the CJ750 sidecars shop) and we did the whole process in 3 hours to register everything and to get the plates. Incredibly "mafan", but it's done now !

Everything is under my name (all the documents, bikes & plates registration), I chose the plate number, and the bike is running flawlessly, handles like a bicycle, I finally can ride after all those months of paperwork, exams and wait !

I'm really really glad I did all that, glad I'm 100% legal, now I just have to try to stall less when the light turns green ! ;-))