For the DIY brake cable aero routing, you can consider adding a larger countersink for the cable end so it will be more stable and the cable will have less chances to bind against the lever body. Just a couple of wood clamps to hold the lever body and a drill press should make the job easy enough, Just leave enough material so you dont end up punching the cable housing through the lever body, if you have to suddenly grab a handfull of brakes.

Chombi