The Ready State Virtual Mobility Coach is like having a virtual Kelly Starrett in your pocket.
Sounds like you have reached your tissue tolerance when running. Are you working up and down stream of your low back?
What is causing your back to be “pretty stiff” during the day?
Addressing the elements within your environment will help with addressing the cause.
Have you done any of the pre/post running under the sports section?
Or done a search for low back or running on the archive?