Maybe have two config files, one for the BMC eth0 (that does not need to be overwritten with this 2.0->2.1 upgrade) and a separate one for the switch config that has the “unmanaged switch” settings as default. You could lock yourself out if you configure the switch config wrong but you can lock yourself out now if you configure the eth0 static IP settings wrong so I am not sure that you need to worry about that.