Sometimes door handle sets have something very like Chicago screws to hold the two sides of the escutcheon together.
IIRC they have countersunk heads and the side with the hollow has maybe a 5mm outer diameter of the tube and you cut the part with the external thread down to suit the door thickness. The external threaded parts have plain parts every 10mm or so so they can be cut with snips without damaging the threads.
As the doors are usually about 44mm thick + two times the escutcheon thickness making them about 55mm or so long?
Edit, must read all posts before saying something thats already been covered, nevermind.