@neil Over on qoto.org, the technical toot limit is over 65535 characters, but moderators have guidelines of <1000 characters because moderators on 500-character Mastodon instances have to receive them. My practice is now to use a free WordPress.com site (ingbrief.wordpress.com) with a P2 theme, for longer posts, and then to excerpt from there. https://daviding.wordpress.com/2017/06/12/20130727-beau-lebens-taking-wordpress-to-the-front-end-with-o2-web-video/
Not self-hosting all of my WordPress sites lets me observe the decisions made on a guy I managed CMS.