Sandra, Like Marv said, it's doable. I think there may be a single vertical aluminum stud in the center of the bedroom slide out wall. You would need a stud finder that can be used for metal to find it unless it was cool and damp enough outside in the evening. That's when all the studs on our rigs show on the outside wall. They don't show condensation right away and a very easy to spot. Anyway, if you have this stud in the center you would have to decide weather to go along side of it or cut through it and possibly weaken the wall. Windows can be added but shouldn't sacrifice wall strength just for the sake of having one.