I find that the molded in rod holders on the past and current kayaks are a bit anachronistic. They had their place and time...and that time has passed. I have both the Hobie H-Rail adjustable Rod holders and the The Hobie Adjustable Rod Holder Extender on my PA14. They both work very well, and the extenders make use of what I would otherwise consider a waste of space. I like the way they carry both bait casters and spinning rods much better than my old Ram Tube 2008's. The only issue I see with the extenders on an Outback would be that if placed in the rear molded in rod tubes, they might be to far back to easily reach.
I would have you consider installing the Hobie 21" or 9" H-Rails on your outback. They really allow a great amount of flexibility in mounting gear where you want it for any particular trip. Plus at $25 and $20 respectively, they will not break the bank.
As an example, I mounted the 9" H-Rails on the back of my Pro Angler, which adds even more options to where and what I mount. In the photo below I have a H-Rail adjustable Rod holder, 2 H-Rail YakAttack mighty mounts, and two YackAttack RotoGrip paddle holders (which are pretty freaking awesome and handy in their own right.)