Can I "mix" cor 10 with mild steel plate ?

Hi all, I have a hull, mild steel, and as I'm to start the decks/pilothouse and the specs called for 3mm mild steel plate I thought !.;
Why can't I use cor ten for the decks etc, why, well I'm trying to keep the weight top side down and thought 2.5mm cor ten would be nearly as strong as the 3mm but will be lighter , more rust resistant -- things drop on decks -- I'm just not sure about the mix !! ?? . Pros and cons please gentlemen .

 

yes you can.
Usually, when a hull is built with Corten, the deck stays mild steel. Doing it the other way around does not change things