I also have a TB with High Low issues (not to mention a crooked knee on his high foot makign him wear it unevenly and base narrow behind to boot. He's a mess! But he's sound at 17!)
What I noticed with him is that on the low foot, when I used Soleguard as well as making sure my toe was correctly beveled of course and breakover was in the correct place, it seemed to "inflate" the back of that hoof almost like a flat tire wedging it back up where it was supposed to be. I was able to get the alignment I was seeking or darn close to it simply by adding mass to the flattened digital cushion raising the back of the foot into proper position. Horse was happier and moved great to boot.
Now that I have done some study of my own, IMO, raising the wall alone with a wedge is backwards. The DC and bulbs (usually flat anyway from being run forward) sinks and sags like a you... ( argh! I typed a literal UUUUU and its auto corrrecting it to you!) between the prongs of the shoe unless you also use a pour in pad. Inflate the digital cushion with a pour in pad raising the back of the foot up to where its supposed to be and the wall will come in line with the inside of the foot uncrushing the heels because the weight and force is redistributed properly. Make sense? Its kinda hard to explain.