The Action Packer thing does work really well, I've been using that for quite a few years now. I leave the rear seat bottoms at home if I know I'm camping.
Another thing that I've found to be really helpful for sleeping the the X is to have vent shades on the windows. I like the WeatherTech brand, but there are other brands as well. You can keep the windows cracked a bit for fresh air without a lot of wind or bugs or rain getting in.
I've never tried one, but I hear that some of the 12V electric blankets work well.
The Raingler interior ceiling net is a lot easier on your head if you sit up quickly in the night compared to those hard wire steel shelves I see some people using.
I've found it helpful to replace the interior dome lights in the center and back with red LEDs. You don't lose your night vision or end up in a fishbowl if you have turn on the light in the night. For white interior lights I found some little battery operated ones from Black Diamond that will run on lithium AAA batteries. While the lithium batteries are way more expensive than alkaline they won't leak and destroy the light. I have a couple of those hanging from the ceiling net.
