How to free up some space on your Surface
I was digging around and found a Windows\SoftwareDistribution\Downloads folder that was taking up about 8GB of space. Turns out, you can delete the contents of the folder. I am a happy camper now with about 11GB free.
You can also delete any SoftwareDistribution.bak or SoftwareDistribution.Bak1 folders with no harm to your machine.