There is no right or wrong, you can do what makes most sense for you.
My personal opinion: What you are interested in is controlling the light, not the switch. In fact you could have several switches all over your house, that control the same outside light.
So I would place the light in the outside location and I would not include any switches in the model.
If you want to you could create your own custom page for the living room, that also contains the outside light. Or you could bind more than one item to the same channel and place one outside and one inside, but personally I would not do that.