I too am working through this for 2007 V6. I see that the problem described above (binding, need of spacers) is because, as Kenrr points out, the No. 2 Idler Pulley (16604-0P011) is not the same as the pulley attached to the drive belt tensioner (aka tensioner, serpentine tensioner, tensioner assembly and 16620-31040).
I think the solution is to get the correct pulley and part number rather than trying spacers. Specifically, note that the drive belt tensioner (and its pulley) is essentially at the center of the Rav4 V6 pattern of pulleys driven by the crank shaft and serpentine belt. The drive belt tensioner is spring loaded and is what applies the tension to the entire serpentine belt. It is completely different than a No. 2 Idler pulley.
Also note that the T-SB-0056-09 does not have a Rav4 V6 specific diagram because it applies to Highlander, Camry, Sienna, and Avalon. The TSB clarifies that there are two No. 2 Idler pulleys on these models, but only one on the Rav4 and Highlander (because the electric power steering in those two models is not driven by the belt).
The tensioner and its pulley is not the subject of the TSB and it isn't even drawn in the diagram of the TSB. Based on being under the Rav4 itself, I think the absence of the tensioner from the diagram might be throwing people off. If you trace the dotted lines on the diagram, it is clear that the one No. 2 Idler pulley is at 12 o'clock while looking into face of belt pattern of the Rav4 V6 subject to the TSB, which is above the tensioner's pulley at center of pattern (although not shown). The other No. 2 Idler pulley in the TSB diagram (shown to be left of the water pump) is the pulley that is not on the Rav4 V6 (I can't speak for the I4).
I guess it is possible one's drive belt tensioner pulley could be squeaking. If the easier replacement of the No. 2 Idler pulley doesn't fix the chirp that I have, then I will turn to finding the part number of the pulley attached to the drive belt tensioner. If that doesn't fix the chirp, I hope it is not coming from the drive belt tensioner assembly itself (approx. $185) because it appears to be buried/attached to a/c compressor, and not a simple task.