I know how to make a selection lasso LMB, but i do not know how to do is lasso auto select back part of the model RMB.
Maybe press z to enable wireframe (with or without pie menus), so that you can see the back of the model, and select it. More details plz.
To fully understand what I need, you have to try Modo.
My english does not allow to explain in detail
may have an addon that will add such an attribute?