Have you tried using the .WinchEnabled property? It will slowly (or quickly, depending on how you customise the winch properties) pull in/out from I believe Attachment0. You can find out more about the winch properties here:
Honestly “it pulls you forward” actually sorta resembles real life how you like gotta counterbalance the fish you’re trying to reel in, so maybe it would be a cool mechanic that you actually needed to like counter balance the fish’s weight by walking backwards, but it’s just an idea
I suppose you could try and change the WinchTarget value so that it doesn’t reel in all the way, forcing the buoy to remain down. It’s quite hard to think of what to do in situations like these when dealing with the physics engine.