You will be hard pressed to gain strength from the workout you posted. Plus the "leg day" pain will be much worse than any pain you felt during SS.
I know SS is 'written in stone' but, if you're tired from/of all the squats then just drop a session (the lighter one, day 2 I think) or both even and replace it with something else. Nothing's stopping you from putting in some box squats or fronts squats. Ripp is old, he doesn't have the energy to come and hunt you down because you changed his beloved program and didn't drink enough milk
Why do you think your gains have stopped? Are you still getting stronger and better in the mirror? The scale doesn't always give you the full story. What's your diet like? How is your progression planned? etc etc