just got my zdz 80
I started flying Giant Scale in 1982 with a Quadra 35 in a Nosen Citabria and have also never seen a fire in a gasoline powered plane. So, Guess I'll won't worry about it.
I still think the short piece of can behind the engine would be a good idea to keep any gasoline out of the cabin. I would cut the hole in the firewall so that the can just slipped in side it and then I would glue it in.
To get maximum cooling for the engine I am planning to build an air dam into the cowl so that all of the incoming air is forced to exit around the fins. I also have an air chute behind the engine just like on the full scale Decathlon.
Ken