alt Hacker NewsThe "joy of the XKCD technique" is that it prescribes a specific format millions of people will use, and it's so trivial to break that you can throw it into your cracking algorithm at virtually no cost.
If you were willing to use a bespoke, more secure variation of it, you could include a capital letter and a number rather than filing an issue on a repo insisting that you be allowed to use exactly the insecure variation.
I think you are both greatly overestimating the number of people who remember what xkcd is and their willingness to do what a webcomic prescribes uncritically. What you describe as "bespoke" is likely the normal way someone might use it: with their chosen format.
For instance, I have multiple separator characters, multiple beginning and end characters, and numbers places at specific places, and arbitrary casing. That may be overkill but it's still essentially the xkcd format.