I had good success some years back with what you are calling "wedge shims". I was in a softer boot and my feet naturally pronate (arches fall, internal rotation of the foot, wear the inner heel of my shoes more quickly). The combination of soft boot and biomechanics made it less natural to get on my outside edges. My LHS shimmed the back post of my holders on both skates. The shim took up only the external half of the mounting area (from centerline to outside of heel) and was placed between my boot and holder, held in place by the rivets. With a bit of experimentation, we got to a place where I was much more neutral on my blades. I've also at times experimented with heel shims inside my boots. These are common in the sport of cycling to correct biomechanics against a fixed pedal surface. There are a lot of similarities from that perspective. Both approaches had similar result to re-mounting the blades further to the inside of each foot, but no extra holes needed to be drilled. I've found for the most part, people typically do not move the holder position in hockey (like they do in speed or figure), but instead shim to adjust the natural balance point.
I've found a stiffer form fitting boot (True TF9) reduces my pronation and need to shim. That could just be correlational, since I am now skating way more than I was back when I had shims and have built up a lot more strength in all those little muscles, but there could be something to it.