Instead of manually reordering clauses, etc, you could just run the original essay through another LLM without watermarking capability and ask it to write a new essay based on the original.

Then test the result against your own plagiarism detector and iterate through the watermark-less LLM until the resulting essay passes.

Or just proactively run it through a bunch of times.

Or just use the watermark-less LLM to begin with.. personal, unshackled, powerful LLMs are definitely on the trajectory we're headed in.