Simple IK question

[DNorman]

I am not sure of the “correct way” to do it.

You could try this method (the answer marked as solution) it is a little complex but will work well for getting your truck and trailer (or multiple trailers) to follow a curve forwards and backwards.

Line of Bones to Travel and Conform to Curve (Train or snake following path)

I also found this Tutorial but it does seem more complex when you get to do the animation and it involves the rigacar addon

Rig and Animate a Semi-Trailer Truck in Blender: 8-Minute Tutorial | Gachoki...

EDIT (again!)
I have adapted the file I did for this answer (last year) to include a trailer, it uses the method explained in the stack exchange link.

Car follow path and wheel rotation

Here is a simplified example: CarCurve.blend (871.0 KB) To fully understand it I recommend you recreate it reading carefully Batfinger’s instructions in the stack exchange thread to create the control mesh and bones. He uses a simple line of vertexes with vertex groups, I made an arrow shape, (a simple line of vertices may be more accurate but also more tricky to select) He was using the z location of the control mesh for the curve modifier I used the y location, you may have to try differen…

Here is a new file with a trailer!

TrailerCurve.blend (132.2 KB)

you can scroll forwards and backwards, the wheels rotate correctly and the front wheels even turn into the corners (a bit exaggerated but you can tweak that by shortening the front bone and vertices of the drive control object.)