I haven't maintained a Vim config in a few years now (more of an Emacs man now), but I do remember using Goyo in college. Looking back at it, I think it might scratch your itch as far as Vim plugins go, it even allows you to resize the area on the fly.
Goyo is one of the plugins I experienced as brittle and cumbersome. IIRC it creates the centered text area by creating 9 windows. The outter 8 to center the one in the middle, which is used to edit the text.
In my attempts to use it, that created a bunch of issues.
https://github.com/junegunn/goyo.vim