Just wanted to let you all know about my findings. I did find a set of 6.5" speakers that fit in the door of my 02 wrx wagon *almost* perfectly. I didn't even have to make a spacer because they came with their own. The bolt holes *almost* lined up perfectly, but I did have to drill 2 tiny tiny holes in my door and use the screws that were supplied with the speakers.
The speakers are clarion "SRR1626" 6.5" coaxial speakers. I did not take any pics during the process, but it went pretty smoothly. There was 2 approx 1/4" spacers/brackets, 2 speakers, and 2 thin metal mounting brackets I guess is what you would call them. I put the metal pieces on the back side of the speakers mounting flange, and then the plastic spacer on after that. I screwed the speaker into the spacer, then screwed the spacer into the door. Had to slightly drill out the holes in the thin metal spacer just a little bit so that the screw could go through it and into the plastic spacer.
So far they sound great, and there is no interference with the window at all. I may take the door back apart to take some pictures. Let me know if there is anything else that you want to know about it.