Update your allocated ram for Minecraft to at least 4GB. In your crash reports it shows you only have 3GB allocated as denoted by line 99 of Error log 31ujkJM4. SkyFactory requires at least 4GB of memory to load and run. Also, while it is not directly related to the crash, I would recommend updating your installed Java if possible, as the current release is Java 8 update 121 and according to the log file you are on Java 8 update 25. This is exposing you to possible security vulnerabilities.
Try increasing your ram amount and see if that helps. I am one of the Admins for TeamIHOC, and we operate an open public server that is currently running SkyFactory 3 and have not seen this specific error so far, however 80% of the problems we have seen are directly related to less than 4GB of memory being allocated to Minecraft, which is what line 99 is showing here.