Would a hard bronze washer between the a-arms and the frame mounts to separate the coated (paint/powder coat) surfaces help reduce the chance of squeaking? These would be wear items that would require periodic replacement, but if it eliminates the squeaking...
I did a bad job of explaining the issue as I made it sound like it was the powdered coated a-arm rubbing against the powder-coated frame. It's actually the center of the inner heim joint of the a-arm as it's mounted to the frame. The bolt going through both leaves just a hair of slop between the bolt and the hole of the heim joint. This small amount of slop allows the center of the heim joint to move and rub against the edge of the mounting tube (that is powder coated). I filed off all of the powder coating off the mounting tube for the bolt on the frame so it would be metal to metal contact. This allows the two metals to be clamped down better without the "rubbery cushion" of the powder coating between the two surfaces.
No one is really going to understand what I'm talking about here. It's difficult to describe.
The surface of this tube as the heim joint is mounted to it is what was causing a lot of noises for us. The bolt can allow the heim joint to move ever so slightly against this surface. At first I over-torqued the bolt to tighten it and it helped but that's not the best answer.
The lateral movement of the joints cause a rubbing noise. "But how, Chad!" "How can this happen while I'm just turning the steering wheel?" Turning the steering wheel applies a force to the wheel/tire that resists against the ground thus forcing all the other components move. If you jack up the front, you probably won't hear it since there is no resistance.
Now with this being said, this was OUR issue. It may not be your issue and may very well be something else. But it's something to consider as it may kick your ass otherwise. This can also happen on the lower arm, I just showed the upper because it's visible in the photos.
Good luck!