My problem comes at trying to deal with quoted strings containing bracketed text...

That's pretty much where one always runs into trouble when using a regular expression to parse balanced text. Now that the (?{...}) and (??{....}) directives exist, it's possible, but messy. This is discussed in perlfaq6 under the section addressing balanced text.

This is why mankind invented Text::Balanced. As the FAQ states, you might also find helpful clues in Regexp::Common.