Separation anxiety

Our Gus is 2 and has severe separation anxiety. I’ve recently considered sending him with a recent rehome, but I want to know that I tried every single thing before hand. We love him and really don’t want to get rid of him but he poops everywhere every time we leave. He is completely house trained but his separation anxiety is so insane. I recently bought one of the balls you put the treats in and they have to work out. No luck he wasn’t really interested. I try leaving one of my shirts with him. Someone please help me. Any recommendations?