One of my best friends has a tickle fetish. She never talked about it all our years growing up. She finally confided in me a few years ago (in our 40's). She felt like it was the most taboo thing in the world. Of course, she physically likes to do it, unlike you who only write and imagine yours.

She found a forum for others with the same fetish where she writes her heart out. They gave her an award!

You seem like you'd be a good writer. If you get brave, post one on here, but add the Trigger warning.

Also, I found a writer's group for screenplays. There was this guy that wrote the most violent works you could ever imagine. We were all scared of him killing us all. But he was a really good writer and his screenplays were actually good, although they would never actually be produced.