I'm fairly new to these trucks too and still learning but here's what I what I have experienced. Although I do have larger injectors and an upgraded fuel pump, it should not matter at stock boost. The stock system, although marginal, should supply enough fuel for stock boost levels regardless of the octane. The factory just did not put a system in that would support "turning it up". So, if your stock system is up to snuff you should have no problems with the amount of fuel at stock boost levels. This is where things such as a fuel pump hotwire kit can help your stock system perform it's best.
Not enough octane can definitely cause knock but it is not the only source. Running lean, too much timing, too hot of a spark plug, plug gap, carbon build-up, high air temps, engine temp, and mechanical problems (bearings, mounts, the exhaust system hitting the frame, etc.) can cause knock or be picked up by the knock sensor causing the computer to pull timing. The tricky part is figuring out just what is causing it but if you have a stock truck running stock boost, 93 octane fuel should not knock at 15 pounds provided it is a quality fuel and is accurately rated. I know sometimes fuel varies by region or time of year but 93 should be 93. It's not a Sy but on my Buick I wouldn't start seeing octane related knock until 17+ pounds on the stock turbo.
In my truck I run a Turbotweak chip with everything set to stock. I run pump 93 with no boosters and I get no knock at wot. I will occasionally get a couple of degrees retard due to transitional knock (going from cruise to wot or at the shifts) but it goes away immediately. Of course my truck is street driven and not tracked so no heat soak to deal with on my occasional wot runs. I have also heard that the fuel quality has changed and if you are still running the stock chip, the timing might be a little aggressive for today's fuel so that may be an issue. An aftermarket chip might help in that regards. Eric at Turbotweak would be the one to talk to about that to see if that could be an issue especially if your knock goes away with just the addition of octane booster.
HTH