Looks like a nice trip. I am probably going to go camping next week. But it will be down in southern Utah, Arizona, Death Valley. Like you I found my first mattress to soft. I was sleeping on the floor in the bottom of a 5 inch hole as my first foam was way to soft for me. This is what I tried next.
Foam
I now have 5 inches of that stuff. It is now just a bit to hard but is a whole lot better than before. I have the memory foam toppers. Took them off, just not for me. If I was to do it again I might get 3 inches of this foam and put a softer kind on top of it.
Randy