u/Just-Asking-Jones

I just got a Tentbox Go, taking a road trip with my dog in June. I'd like to be super comfortable and wondering what advice is out there. Tentbox offers a 'mattress' that looks to me like a good foundation to put something else on, another mattress plus duvet maybe? Not sure how thick it can get and still be able to close. Anyhow, I'd love suggestions! Used to be totally comfortable sleeping on the ground, but I"m older now... ! Thanks!