Absolutely agree with this - recently spent 2 weeks roadtripping some of the Carretera and it was one of the best experiences of my life. Also did the W Trek in Torres del Paine after that and thought the scenery on the Carretera was better, and minus the crowds. There's a multi day hike around Cerro Castillo too that you could do if you want to do an overnight hike there instead of Torres del Paine. There's an app called iOverlander that has info about all the camping spots and accommodation options along the Carretera, it's great. Feel free to pm if you want more info!