If I understand your dilemma correctly I think you are afraid that by enabling RADIUS AAA on all of your APs that if you do not have your RADIUS database properly preconfigured then any SMs NOT configured would then NOT be able to connect to the network and would be stranded.
If this is your concern then you could preconfigure all of your SMs to have the same AAA Username and Password before turning on AAA. Then your database would only need a single entry.
Mass configuring your SMs should be possible with a template via cnMaestro.
Once all of the SMs are connected via AAA/RADIUS you could then work to setup unique configurations for each SM in the database and push these changes via DHCP Option 66.
I am sure there are other methods, but this is the first that comes to mind.
I hope that helps. Let us know if you have more questions.