Please use readmore tags! The spoiler tag has four different display options, including a table view. Thus usig the spoiler tag to save space does not always work.
I did use readmore. I used the spoiler tag inside the readmore. The rules may have changed, but at least it used to be that you couldn't use a readmore tag inside of an existing readmore tag.
If combining readmore and spoiler with some display option causes the readmore to be useless then I'd call that a bug in the site, and not a mistake in my post.