What your boss can or cannot understand is totally subjective so I am afraid you will have to argue each feature with him. You can start with the kind of "baby Perl" that he has defined and try introducing new features slowly, showing him how they work and why they are useful, maybe by writing snippets 2 different ways, one that conforms to the current directives and a simpler (and obviously easier to understand) one which introduces a new feature.

This way not only will your boss learn more Perl but you will learn how to teach it.

One thing I would definitely not compromise on would be the use of strict and -w though. These make the code safer, cleaner and easier to read. Declaring a variable (and initializing it if need be) is the perfect place to comment its role. And I really don't see how they can be described as making the code more complex. What part of my $total=0; does your boss not understand? Especially if written as: