Text body on same line as heading

Even though perhaps typographically unsound, is there a way to put text body on the same line as a heading, directly after it?

I.e: instead of:

Text body...

I’d get:

HEADING 4[some larger space, or user definable character] Text body...

My motivation searching for this over simple formatting text directly is that I want the heading structure to remain valid. Perhaps a solution using lists (if possible) would also still be acceptable.

As you have been answered on IRC, this is impossible, and this is tdf#48459. A workaround using index entries has another issue: tdf#65463.