had the same 'problem' but found out that you can have an MBean do depend only on other MBeans - not on a war.
One solution might be to pack it as a russian doll - pack the war inside your sar. Then the war will be deployd before your sar. But on other hand - you also says that you sometimes don't want to deploy the sar at all... Your way to go might be to change the deployment sorter to match your needs instead.
When you deploy a .war file, I believe several MBeans are created. You can check via the JMX console which ones these are. I think at least each Servlet creates an MBean.