I'm begging Jesse to keep those properties modifiable at runtime!

It would just provide so much flexibility that would come in handy for operators.

  - One can control this feature from $JENKINS_HOME/groovy.init.d/*.groovy. When these are managed by Chef/puppet,
    this make it very clean to apply this as a patch.
  - The log file is getting too big and wants to rotate? No problem with quick groovy script from the console
    (or from CLI if you need to do the same with 12 masters)
  - Shipping the log over to network instead of local file? No problem!

I thought your primary concern of field being unreachable from outside is already addressed via @Restricted(NoExternalUse).