I'm sure it's faaaaaar too late to be useful, but I just came across this and figured I'd add my 2 cents. (note I didn't test it, and I'm curious what your solution wa)

1) change your activation SP. Write to a different database. Tell your activation sp to ignore records going to the new DB and not message_data.value('(/EVENT_INSTANCE/DatabaseName)[1]', 'varchar(128)' ) = 'yournewdb'

2) change your activation SP. Add an account and run the activation SP under that context. Now, tell your activation SP to only insert when the loginname is not your new account.

3) send to a secondary server. (Not necessarily very easy, but definitely doable)