This solo strat works well almost all the time, and having a player play this every couple of rounds will deny Ts a comfortable route to B.
This strat is based on the fact that most Ts will not clear Secret after they have gone behind T Red. Most of the time, they will clear it from Silo early in the round, and never check it afterwards.
As a CT, take this route. Through Hell, Ramp, then Jump through the Window on B, and Go through Tunnels to Secret. By the time you get there, rushing Ts will be at T Red, and you can get an easy pick. However, if the Ts are not there, you can clear Silo more easily than people in Garage can, and you can also rotate back to defend B.