You could store the log4net configuration in a database (you could then even consider to create a web interface that allows your QA team to modify the configuration). You have to figure out how your applications pick up the new configuration (e.g. you have some remote Admin interface that allows you to tell your applications to use the new configuration).
On start-up you load the configuration from there. Maybe it is advisable to have some backup configuration in a file that is loaded first in case loading from the database fails. The default configuration would be for instance so that the QA team gets an email if loading the configuration from the database fails.
Another option would be to store all log4net configuration files on a network share... create an application setting that tells your application where to find the log4net configuration and call the Configure()
method accordingly. Again the question is how your applications pick up the new configuration.
Not sure if ConfigureAndWatch() would behave as expected if the configuration files is on a network share. If so that would be quite an easy option to implement.