Downriggers are almost required for this fishery with the added bonus that when done right, you typically catch small chicken halibut while trolling.
I first tried a gimbal mount. I had to modify slightly but the stainless mount I got was HARD! Could not drill through it with titanium coated bits. That's another story.
Re-read ZEE's great article and decided to center mount it behind me as suggested. I was concerned I wouldn't be able to reach it but it turned out to be no problem.
There's been some discussion on what pound weight to use. I would say that from my ONE time out. I would say a 6 pound ball is MINIMUM for trolling saltwater salmon gear. I still had line angles approaching 45 deg when trolling fast and against current. 90% of the time, it was within acceptable range of angles.
What struck me as amazing was the zero tippininess factor. I was delicately placing the ball into the water fearing it might yank and cause the kayak too tip a little. Heck in my outback, I could have shotputted the weight out and I don't think the Kayak would have flinched. ZERO scariness factor I was thinking might happen. I will say I use a large 17ah battery I mounted inside on the side opposite of the downrigger for balance.
The only drawback was it did feel like you were paddling through "thicker" water. If this was the only thing I did in my outback, I'd consider putting the original fins back on. But it wasn't overwhelming. You could just tell it was "more" effort.
The fish better watch out! I really think this is going to boost my productivity on salmon considerably.