I just finished an overnight trip from St Louis to Marshall, TX and found the seats to be fairly uncomfortable for sleeping. There was plenty of leg room and I liked that it has the leg rest you can pull up, but when I tilted the seat back, it caused me to slide forward and put all my weight on my tailbone, creating a very uncomfortable hotspot. I also lost all lower back support in that position. I'm going to buy something for the seat before my return trip on Monday night. I thought about the swim ring, so I may try that. I was also thinking about the long blowup pool pad as it has a pillow on one end and if it's only filled up half way it should bend to fit the seat, but I'm afraid it's too wide for the seat.
Also, I've learned I need to bring a light blanket or wear a light longsleeve hoody. Even in the summer, it gets surprisingly chilly at night.