WWCD? (What would Conway Do?)
...Break long lines before an operator. That approach ensures that each line of the continued expression will start with an operator, which is unusual in Perl code. That way, as the reader's eye scans down the left margin of the code, its immediately obvious that an indented line is merely the continuation of the previous line, because it starts with an operator.
The indenting of the second and subsequent lines of the expression is also critical...they should be indented to the starting column of the expression to which they belong.
Hence, ikegami. (Although Conway likes to put the terminal semi-colon on a line by itself, to signal completion of the multi-line formula.)