I had the same experience. Writing something like lemmynsfw_dot_com so that it isn't recognized as an URL (still) works.

A guess spanking is already covered in the light bdsm stuff.

You could try CFNM (clothed female, nude male), which can also be applied to not explicitly sexual contexts.

It might be worthwhile to cross-post to https://lemmynsfw.com/c/femdom_community

It's better to use an image host to not overwhelm the instance.