For my Focus, RIP , I had some flexing issues both inside and outside the fuse. I joked that I should write an article on how NOT to install DEPS!

Anyway, the distance on the outside was about 9 inches, but the rods didn't come directly to the horns. So when everything was hooked up, there was a slight bow of a couple degrees to the elevator surface horn. It flew okay for about 30 flights but then I started getting flutter. When I inspected it closely it looked like the hardware had worn just enough, barely perceptible, to let the elevator start oscillating. Just as a test, I tie wrapped another rod next to the exposed rods, kind of like Steve was suggesting, and tested it at home.

Looked promising so I used some 1/8" carbon tube like Troy suggested and the results were very tight. On the inside my single rod to the sleeves was too long, so once I fixed the problem on the outside of the plane, if you held the elevators under load, the Y on the inside would buckle under load. A couple sticks of 1/4" sq. in the right place fixed that.

The 1/8 tube should work pretty well Chris, it may look ghetto to you, but I would bet most wouldn't notice it.