Sleazy Fork is available in English.
Loads manga chapter into one page in a long strip format, supports switching chapters and works for a variety of sites, minimal script with no dependencies, easy to implement new sites, loads quickly and works on mobile devices through bookmarklet
Found newer script that works (including 8muses), since this one isn't updated.
I'm not affiliated with this script, but I found one that does the same job, and is up to date: https://github.com/TagoDR/MangaOnlineViewer
My suggestion is to click the settings cog on a given manga page, and set it to "theme: dark"; "default load: Never (manually)"; "show thumbnails" unticked.