I don't think it's a very good idea to include content when using twtxt as a syndication format. Anything based on twtxt, in my opinion, should retain the spirit of the original specification, especially readability by humans and machines. 10K of HTML in one line absolutely breaks human readability.
What about
TIMESTAMP\tTITLE\tPERMALINK
, like the following?
2022-09-22T14:53:26-07:00 Bringing Back a Useful Browser Feature With a Bookmarklet https://mckinley.cc/blog/20220922.html