Do you hear knocking while Offroad, going over rocks, or speed bumps? If the answer is yes then get UCA’s
Can a shop not get a complete alignment for camber? If yes then get UCA’s
They arent necessary if you answer no, but it never hurts to replace them in the future for more durable/stronger one.
The Tacoma is wide enough for anything you’re attempting, clearance is more an issue than anything. Wheel spacers should be avoided du to the change In weight distribution to the hub/bearing and change in geometry. This can result in premature failure of your bearing.
That being said it’s advised to go with a true hub centric spacer from a company such as spyderco due to the build and material used from said companies. Avoid lug centric.
Dirt and grime can get trapped in between the leaf packs which over time can cause the squeek, you really have to just live with it because there’s no way to really eliminate this.