How to place the origin of a pipe at this specific point?

[JesusChristus]

I have this construction and I want to create a pipe cylinder ranging from the tips of the zig-zag line to the other side.

The zig-zag line was created with a simple line sketch that I turned into a pipe.

The new pipe cylinder should reach from one point to another like so.

The pipe cylinder must be centered at the center face of where the pipes from the zig-zag meet.

I tried it two ways:

1. Create a new pipe on the YZ-plane and then create a pipe cylinder on the center point. But I am unable to select the center point.

2. Trying to create a construction place centered on that point. But also here I'm just unable to select that point.

I need help to get this centered at that point, that I just can't seem to select.

I'm working with parameters of length, height and width. It would be great, if the pipe cylinder could be created in such a way that it automatically stretched when I change the length of the entire construction.

[davebYYPCU]

First - Pipe Tool requires a Path to follow.

To connect the bottom point of both Zig Zag lines, you need a path from front to back attached to both of those points (Red Line.)

Create a side on sketch plane, Offset to Object, and select a Zig Zag point.

Put the sketch on the Offset Plane.

Project > Intersect the zig zag Line to collect the purple points.  

Join a line to both purple points.

If you move the spacing of a set of posts, the line has to update.

Might help....