control persistence

We are using your persistence/IO system to save the QAT out so customization changes can be maintained. We are also looking at doing this for the command ribbon bar using your xml I/O. But we have an issue because the data we save may become invalid (command IDs are not always constants due to add-ins, automation etc.). I need to be able to store something more than the tag (which is a dword_ptr). Storing a string where I can persist a com CLSID and other information would be very useful in allowing me to rebind the control to a particular server.

 

But I don't see anything I can set in a control to accomplish that as apparently the tag is all I have to work with (everything else appears to be used by your system). Is there any string or binary data I can store in a control that you will save/restore that I can use? If not, can I subclass and somehow get into your I/O stream?