And it feels to me like being able to cogently answer questions on StackOverflow isn't a skill that's necessarily correlated with architecting big systems. The value I'd imagine you have, out of this skillset, is being able to explain your code to other developers, give good code reviews, figure out new systems, etc.
If it were me, I'd mention it on my resume and give it some wording in the hopes that an interviewer will ask me questions along those lines and ask me to explain some code and I'll do a good job of it. But that would also be selecting for jobs where my work does involve a lot of working with other coders and doing code review, and not speak very much to my ability to do architecture and design review.
(Or maybe I have the wrong impression of what all this is about, and you should take me as an example of a naive interviewer and correct for that. :) )
I have yet to meet anyone who would take internet points as IRL credibility / experience (to my disappointment).