Position of joint endpoint on rigidbody

Hi, I started working with unity 5 days ago so it may be a very trivial problem, but I haven't found any solution (or didn't manage to apply the solutions I found to my specific case).

Background: I'm creating a mod for KSP which allows the user to create struts (joints) between parts in flight (in game). There are two ways to create such a connection:

1. Putting an origin part on one body, a target part on another and creating a connection between those two

2. Connecting a origin part to another body without an explicit target part (imagine a rope with a magnetic hook or something like that)

Now my problem: when I don't have a target part and create the joint directly with the rigidbody of the (big) part all forces applied to the joint seem to be applied to the center of the target part instead of the position of the visual strut.

Since it is a bit difficult to explain I created several screenshots and a graphic (in the screenshots red is the force and blue is a point where the white cylinder is mounted free moving and can rotate (the axis)):

1. Basic idea of how a body should react when forces are applied to certain positions (assuming center can move and is somewhat fixed)

2. How it looks like when I'm attaching a target part and connect origin and target - that's how it should be

3. How it looks like when I'm directly attaching to the big white cylinder. The force is strong enough to flex the part the origin is attached to but the white cylinder stays in about the same horizontal position.

Can I tell the joint somehow that it should not be attached to the center but to exactly the point the visual strut hits the target?

Thank you very much in advance!