Edited Post: Below is my initial thought on how to do this, but as Yolette reminded me, there is a simpler way! Please check out my post on how to insert a “read more” tag.
Um… never mind this idea! We could use the main body of a post and headline (which denotes a spoiler comment) to start the content and indicate what the spoiler would (very generally) be about, and then put the body of the spoiler into the comments as a Reply, but not referencing the spoiler in the first sentence or two, please.
There is an option to view/not view comments inline, so you can turn off the inline viewing and not see the spoiler if you choose not to see it. For the more spoiler averse – that is, everyone but me 😉 – you might want to do this as a general rule!
Under the bell icon in the top right tool bar you can see the gist of what a post or comment is about but it only shows a fraction of the first sentence. In the Most Recent Posts and Most Recent Comments sections in the right column widget sections you can go directly to the posts of interest as well.