Attach a fender board on your starboard side. Lay up against the piling like the blue boat shows. Run a line from your stern cleat, around the piling, and back to the cockpit. Put the engine in reverse, hold the line, and the boat will pivot back into the slip. You "steer" by how much line you let out. This technique is easy and works really, really well. It does require that the neighboring boat not stick out beyond the piling, but you said that's not an issue.
I love that idea. I actually saw that technique taught by an ASA certifying instructor during an ASA instructors class. It was very impressive.
The boat was something like a 38' late model Beniteau with something like 80 hp engine.
From a practical point of view however I have several problems.
I'm not sure I could position the boat on the fender board by myself, he had 4 instructor candidates available and we were all fending off. I would only have one shot and have to hit the exact spot. Too far forward and my bow would go into the next slip. Too far back and I would miss the board.
I really doubt if the engine has enough reverse to make this happen.
The biggest problem however is I can't think of a way to test this.
Maybe 4 guys and towboat.
I like it though in theory and I have seen it done.