I bought the, either Zinus, or some other brand that was Green Tea themed, off Amazon for my van. Don’t remember cause it was like four years ago. It might be a 6” tho, not a 4. It’s super comfy with a 1” egg shell on top. Check out Amazon for 4” mattresses. They ship in a box and come rolled up, and then ‘inflate’ when you roll them out. And they’re easy to shove into the corners of your van if your bed is slightly smaller than a standard mattress size. These beds I find to be “firm” so look for a topper if you need extra squish. Good luck! More on reddit.com

Density really does matter in a mattress topper. I have many, many different toppers of different densities and my favorite, by far, is the 4lb topper from Foam Factory. They can send you sample cubes ofwhatever you like and at least you can feel the difference in “squishiness” between them. The 4lb has some heft to it and feels much more supportive than the 2.5lb and something like Serene foam. I also had a Viscosoft topper, and that, at 3.5lb density was way, way too firm for me, but I weigh 132 and am a side sleeper. It was an excellent quality topper, and I can see it working for a lot of people. More on reddit.com

Really depends on the density of the foam. If it’s super dense (like a backpacking camp pad) then 1/2” is enough. If it’s a softer foam, your hip may still hit the wood even at 4” thickness. More on reddit.com

I am grateful for the 6 inch when I sleep on it. I wish I had got the 4 inch when I have to store it. If I had it to do over, I would still get the 6 inch. More on reddit.com