Getting shadow artifacts after baking

After baking a single directional light in to my scene I seem to be getting these shadow artifacts on certain vertical surfaces. I've done a lot of reading/troubleshooting over the past 24 hours (many of them spent rebaking) and managed to reach this point so far:


Aside from the settings above i'm working in linear color space + forward rendering, very high quality/high resolution presets selected where ever possible. All other settings default.

Am I heading in the right direction in trying to solve this? Anything else I should be looking at/trying? My last bake took 4+ hours so any advice before I try another round of settings would be appreciated, have only been using Unity for a few days but have picked up a lot in a short time. Please help!