I don’t think you will even need to type yourself. Tools removing the watermark will be available 3-4 days after this hits the market, fully able to be automated. Watermarks are not a solution that will prevent someone who wants to deceive you from doing so - only awareness that everything on the web is sus will.

Edit: The only alternative is an 100% digitally signature authenticated web, from the web login down to the posting. I am not sure this is a better way because it also means 100% transparency of everything someone does.