Here is the link to our VANOS Cover Cups. Spring covers that are captive under the central bolt are the only truly permanent solution. There have been plenty of threads where snap on covers have failed- it's just replacing a failure prone part made of plastic with a failure prone part made of metal.
https://www.m3post.com/forums/showthread.php?t=1937182
The S65 engine timing is one of the easiest across the BMW engine models. We also offer tool rentals and install kits to make it as painless as possible.