a thin spacer between the batteries and the bottom of the battery box?

Hi, Pulled by old batteries yesterday. Have new ones ready to go in, but will clean, de-rust, and paint the inside of the battery box first.



The batteries (2 ea group 24's) sit in a very shallow plastic tray, which sits on the bottom of the battery box. Between the plastic and the metal box, water remains trapped, causing corrosion.



Is there something (needs to be very thin) to raise the plastic tray just a tad and allow some ventilation? Thinking some stainless steel or galvanized vent screen? Or some plastic product??



Thanks,



Don