I’m like you and prefer a GUI, I currently use FreeFileSync to keep my site synched up between local and server copy.
There’s a RealTimeSync feature that do what you want: FreeFileSync
Note that you’d need to pay for the Business edition (20 euros) if it is for commercial use.
I’d be careful with real time sync though. It may cause issues if you and the client edit a file at the same time, and mistakes are immediately synced to production. Personally I wouldn’t do it esp. when it’s your client’s website.