Well, our brand new Zonesleep lower topper has had a 3 night trial - first night on our mattress at home, second night upstairs in the Cali and the third night downstairs.
Definitely WAY better than our existing memory foam topper, even though it's less than half the thickness. On memory foam I find myself having to roll from one side to on my back to the other side periodically during a night to get comfortable. With the Zonesleep I don't recall waking up once and having to roll over during the whole weekend. Maybe I did, but I didn't wake up! It was perfect in the upper bunk. Downstairs, despite knowing they were there, I couldn't feel the join or seatbelt well in the vehicle rear bench seating at all.
So - it works, does everything claimed and is definitely recommended. The best 2 nights' sleep I have had in the Cali so far.
Oh, decided to keep to 65mph on the way back from Yorkshire to Bedford yesterday morning and averaged 39mpg, which can't be bad for a 7 year old 174 4motion.
Happy days - and nights!