I finally changed my belt tensioner and first want to thank Old Tech for the invaluable advice he shared about the process. I'm glad that I read it and got the Harbor Freight offset wrenches before starting the repair. They proved to be the perfect tool for accessing the upper bolt of the tensioner without removing the water pump, as the Service Manual dictates. I didn't take too many photos and won't provide a detailed write-up given Old Tech and Saeed have covered the process rather well in their posts on the matter. However, I will offer some comments that could help:
Much like the radiator cap, the belt tensioner is really something that should be replaced on any Kizashi shortly after 100K miles. These things just wear out and, per Old Tech, are killing Kizashis that overheat as a result of these parts failing. While the tensioner was recalled for the first year models, I think all tensioners should be replaced as they age, just like the belt itself.
Also, since July or so, I noticed an odd sound coming from the engine in my Kizashi. It was faint at first but got louder. It was an odd shuffling-like sound that was likely a bearing wearing out on one of the pulleys of the serpentine/drive belt. It's easy to ignore or not notice but I often drive with my windows down and listen to the engine at times. It was very noticeable when backing up after parking next to another car (that bounces back the sound). I inspected the belt and it was in good condition as I replaced it less than two years ago but I noticed that the inside top appeared to be wearing a bit more than the rest. The smooth pulleys also had some sort of build-up; likely grime from when my valve cover leaked oil. Given the noise and the tensioner and idler pulleys being original, I ordered new OEM parts from Megazip. My last post on here mentioned Continental idler pulleys I ordered from Rockauto.com but they did not actually fit the Kizashi at all. Hence, I got the OE tensioner and the OE idler pulleys from Megazip.

Once I accessed the tensioner, I tried Old Tech's advice of checking the tensioner by rotating the crank pulley counter-clockwise several times to check the tensioner's proper function. I then watched as the belt started to come off of the pulley on the tensioner a bit. At almost 130K miles, not surprised that the tensioner was in need of replacement.
I then set to replace the tensioner and the two idler pulleys. Accessing the idler pulleys isn't hard if you have a standard box wrench. However, taking the tensioner off requires the offset wrenches. As Old Tech advised, the offset wrenches from Harbor Freight (Item 32042) are ideal in angle and size to access the top bolt of the tensioner, which is near the water pump. If you remove the pulley off of the tensioner, you can access this bolt with the offset wrench. The lower bolt is very accessible and easy to remove. Once the bolts are off, you can wiggle the tensioner off. Keep in mind you need the pulley off of the tensioner to also remove the tensioner itself off due to low clearance however, you really don't need to remove the water pump at all.
Similarly, you need to remove the pulley from the new tensioner first to fit the tensioner onto the engine. This is because you need to angle the tensioner in ways to fit onto the engine and then install the top bolt.
The hardest part of the repair for me was getting the belt back on, likely because I didn't employ a good technique. I forgot from last time that it's best to not try put the belt on squarely in one go but to get it on partially and then pull back the tensioner again to adjust the belt on the pulleys perfectly. Having an ideal wrench of the proper length for leverage would make it easier but the HF wrench did the trick after I improved my technique.
I started the engine to check the installation before putting the panel and wheel back on to make sure. The engine started fine and the noise I've been hearing since July was immediately gone. It was one of the pulleys I replaced; perhaps the tensioner pulley itself. Oddly enough, the engine did not turn off normally. Perhaps it was because the front wheels were both off of the ground and rotating slowly in 1st gear. I managed to turn it off, likely after putting it in Neutral. I've since test driven the car and it's solid. The engine sounds normal and I now have much more confidence in driving the Kizashi without worrying about the tensioner failing and causing potential catastrophic engine damage.