I want to post an essay: a light hearted look at Muhammad/Islam. The essay has 5200 words plus several pictures. Printed out it takes up 17 pages. Is that too much for one post?
It will get read by someone who is sufficiently interested in the topic, IF it is properly formatted into decent paragraphs and headings. If it's a wall o'text, forget it.
However as others have suggested in this format here on this site, it might be better to post it somewhere else and provide a link to it and have your actual post be a summary. For example if you have a blog site, post it there. Or on Tumblr, or Medium.com or something.
That way the short, summary version can be discussed / debated and those who want to put in the effort can read the whole thing.