Ignore 'string to remove' words for certain fields / content types

I tried adding the machine names of the content types/fields to the safe tokens list, but it ignores the string completely. For example, I have a Book content type that I'd want to keep the full title for.

Given the following setup
Strings to remove: ...out, of, ...
Book title: 'Out of Many, 5th Edition'

Current State URL: many-5th-edition
Ideal State URL: out-of-many-5th-edition

Any thoughts on adding this capability to the module?