I've tried disabling colliders which tends to cause passthrough problems as well as reciever targets not reacting to them as if they where a ghost. You can turn up physics springs, dampers, and mas forces if the target atom keeps moving out of the way or even lock them in place but the atoms can start to vibrate and eventually explode when they're subjected to extreme forces.
My best results came from moving the colliders just outside of the target atom but then making them larger in radius and/or height so that there are as few gaps as possible.
For oral insertions moving some or any of the hard colliders that slants downward and towards the back of the head helps guide the insertion to make the 90 degree turn into the neck instead of getting blocked when it meets colliders at the back of the head.
Hope this helps.