Unfortunately, no there is not a way. Apple made it this way so that personally owned devices couldn't be Supervised and managed by someone else. Apple Configurator will always wipe an iPad when you Supervise it and again when/if you ever Un-supervise it. There is no way to Supervise a device without wiping it.
I know its not the answer you wanted to hear, but I hope this answers your question.
A possible solution might be to start from fresh by supervising the devices, but then re-installing all the apps that you purchased with individual apple IDs on each device. Make sure in Configurator that you go into Preferences and UNCHECK the box that asks if you would like to delete apps not instaled by the Configurator.
I was in a similar situation as yours and so far this has worked for me.