Rear Admiral + Rebel Captive + Mara Jade + Isaard + Determination

Patrol Leader + Darth Vader

The first is my prefered build for a Decimator. I know that Determination might not be as popular as say PtL (though why you want to put PtL on everything in sight I don't get). I won't go into why I like Determination so much here because I have a whole other thread on that topic.

Part of the stratagy is one of those jerky tournament things, that says just might not have enough play time to kill one (or both) of my 16 HP ships.

Part of it comes from the even more jerky reaction I had when I found out my LGS only had 2 Decimators in stock. So I bought them both.

However I think a pretty standard 40 point unupraged Decimator was a great back up for my kitted out Decimator. After a few game I found that my original plan (putting ruthless on the Rear Admiral) cost me as many hits as it did my opponent, and it wasn't really as needed for my Phantom hunting as I had thought. (Side Note: Rebel Captive is actually a great counter to Phantoms) So I went looking for a EPT to replace it. Then I had a few more points, just enough to put Vade on my otherwise un-upgraded Decimator. Beautiful.

I like the idea, and don't even mind the "jerky" aspects of your post, but I do see one potential flaw: Vader on your patrol leader. You said that part of your tournament strategy hinges on being able to keep two decimators alive until the time runs out, but Vader works against that. As an opponent, depending on my list, I would probably target down your PL first and then try to keep MY ships alive the rest of the round. Your Chiraneau doesn't have a whole lot of punch to him, so I shouldn't be too hard to keep 2/3rds of my lists alive until the end of the match (again, depending on the list)

Other than that, I like where you're going with this.

Vader isn't there to be used with every shot. He is more there as phantom insurance. Or other high cost, low hit/shield less ships.