Even though the Yough is open year-round in Connelsville, the state doesn't stock it any more. All those downstream areas depend upon the local club stockings, of which there are many. I don't know whether or when any clubs stock in Connelsville, so you may want to check into that ahead of time. The Yough from 381 upstream to Ramcat Run and from the mouth of the Casselman to the outflow is also open and regularly stocked both by PFBC and clubs.
In the Connelsville area, you can be at Dunbar quickly. I believe it has been stocked, but it also holds over fish. It will be populated well if the weather is nice, but if you park deep in the gamelands and walk upstream a bit, you will find some privacy and may even get into some native trout.