Well, you are way past average if you are really carrying a 12.
The simple answer is that the distance for a club is a factor of the length and loft. Wedges with their 35” length have a substantially slower head speed than a 3-iron at 39”. Your pick of a 5-iron length (38”) would increase the speed of wedges, but it wouldn’t decrease the speed of a 3-iron that much—so it would make a good pick if you were to pick a consistent length.
One complication I would see would be your wedge open/close face adjustments. With a wedge with a flatter angle on the shaft, opening or closing the face would mess with the lie of the head a lot.
I will say I have wondered about flattening out the shaft angle by increasing length on my 9-iron and Pitching Wedge (which I don’t really consider a wedge, but more of a 10-iron—I consider my wedges the 51, 56 and 60) I am hitting the 6 & 7 pretty well every time, the 8 is about an 85% success, the 9 and P are 75% good contact.
I ditched my 5-iron and longer irons over a year ago in favor of 3-5 hybrids, and this year I added a 2 hybrid and ditched the 5-wood.
I did just get a Callaway X-Hot 3-wood, which is overlegth, almost as long as my X-460 driver. I think this has helped my consistency with both clubs.