I don't think it is logical to have this on the LCB and I am afraid it will confuse "normal" users, especially new ones, who are already confused enough.
Maps were created as an easy and fast way to store and access data. Much better than payloadXML. Any reason you don't use maps?
I will consider putting an entry in the main window's file menu to open the payloadXML editor. Would that work for you?