A baking oven over 100 C will be at zero humidity. Do you really need to store pcbs/devices at 200 C...this will surely harm some products ? IPC 33B01 allows storage of MSDs in a dry cabinet at less then 5%.....these can operate at room temp or 40 / 60 C. A company called TOTECH has lots of info about dry cabinets and storing devices in line with the IPC spec. You should speak to them.
(http://www.smtnet.com/Forums/Index.cfm?CFApp=1&Message_ID=63231)