I'm switching from three smaller screens to one big 42" monitor with Rectangle to emulate multiple monitors. It works great and I enjoy the flexibility in arranging the windows. However one thing missing is separate spaces. I used to have essential apps / documents on one 'main' monitor with others having multiple spaces. Now I have to switch the whole screen and have to go back and forth to find what I need. It's just a minor annoyance but I'm wondering are there apps to remedy this? By splitting one big screen into multiple smaller, virtual screens.