Pressure treated wood decking ABOVE a painted metal roof

We have a vacation house on North Captiva Island near Fort Myers, FL with a white painted metal roof (attached photo). The roof is about 12 years old and has performed as well as anybody could ask in the brutal SW Florida conditions it experiences (intense heat and UV, occasional heavy wind, and brutal downpours). The appearance is still great, and we have experienced no leaks. The house has a small 150 sq. ft. deck built above the roof, and the decking needs replaced. I have considered pressure treated lumber, but am concerned that treatment compound that leeches out might damage the roof below the deck (I have read on this site that direct contact of treated lumber with metal roofing can result in corrosion). The existing boards have been there since the house was built in 1995. They are too old for me to determine if they were originally pressure-treated. In any event, the original treatment would have been washed away by the time the new roof was installed in 2005. The current boards have been treated every few years with a stain/sealant. I do not want to replace the boards with a composite product to avoid increasing the weight of the deck. (too heavy). Untreated lumber will me anywhere from three times (cedar) to 20 times (Ipe, tigerwood, teak) as expensive as treated southern pine. Should I be concerned about the damage rain runoff and leeching preservative might do to our roof? Thanks for a great forum and a great product! Glen