Help: How can I use a section-view through a complex model to draw a line on a plane?

Okay, so in the image below I have a large pill-shaped structure with three internal ribs and a internal flat floor.

I turned on section view and positioned it exactly where I want a new plane to be. Then I made a plane at that height.

What I want to be able to do is to make lines out of the exterior shell on that plane, as a new sketch.

But because these lines are 'virtual lines', created by the section-view function, I cannot select them in order to import them with 'convert entities.'

And all the googling I have done on this has been unproductive. I feel like there should be some function that will draw a line wherever a surface intersects a new plane/drawing, but I have no idea what it is.

Anyone have any idea? Photos below:

http://imgur.com/8ENHq3P.png

My only recourse, if no one has an idea, would be to cut the model at this point and create actual edges here, try to create a part from those lines, then import the part into my actual model here.

What I want to do with those lines is extrude a piece of geometry all the way around the structure interior at this height, but I need to copy the line of the shell exactly to be able to do that.

Solved: "Intersection curve" Thanks!