See post number 12. I go by 300Dman over on benzworld.org.
Note the 2 pics are of the lower right front of the passenger side (US) floorboard. I did the same inside of my trunk on each side.
Note that this is just for patching up a hole not for an area that has is part of structural support. They sell fiberglass cloth and resin for hole filling purposes. I used what I already had.
https://www.benzworld.org/threads/rear-window-rust-repair.1259945/
There is also anti-rust paint/coating like POR-15 that can be used with fiberglass cloth to patch up holes and it dries hard. I have no experience with it. I wondered why the stuff often came in small cans and I found out that exposure to air hardens it. Hence once the lid is opened on a can the time period to open and use it again plunges.
Air issue is somewhat the same with rust restoring paint from autozone. In about 2 weeks after being opened what is left in the bottle starts to cure.