One of the things I did was call Heartland customer service and ask for the sidewall drawings for my unit. The rep emailed me one PDF for the door side and one PDF for the off-door side drawings. The drawings will show you were the studs are located.
In my model, there is a double-wide stud centered and going from the top of the window up almost 15". So when I get around to mounting a TV bracket I will know where I can drill.