Truck bed, foam thickness?

I have a sleeping platform
It’s kinda hard

wood, carpet, folding “pad”
sleeping bag
It’s thin, compresses, feels like you sleep on wood

I was gonna see what foam Home Depot has
Or a small IKEA topper
Maybe even Costco

But,
I go to a surplus store looking for something else
Low and behold they have all different kinds of foam size and thickness

probably for this purpose. Up to 4” I think
Is it worth getting a sheet? What’s the best thickness?
I’ve found different posts saying any is fine whether it be 2”, 3” or 4”

 

It depends on the density. Also check out camping stores.

 

Back when I had a cap and a sleeping platform. I used a 2" Memory Foam Mattress Topper wrapped with a thick fleece blanket. I bought a full size and trimmed to fit. It was very comfortable for me.

 

got 4x30x72”
long to trim
30” because 24” seemed to thin and 36” too wide to fit diagonally without hitting stuff

hopefully I don’t regret the 4”
Seemed like most popular from googling

2” seemed like not much more than a thin pad when you squish it
But I guess better than nothing
And cheaper

biggest negative will probably be reduced headroom

 

Get at least 4" total. 2" 55-65lb on bottom with 2" softer on top, 35-45 or 45-55 depending on how you like your mattress

 

I recently purchased a Milliard 4" folding cot sized mattress from Amazon. I cut 4" off of the length to fit the 6' bed. I could get by with 2.5-3" thickness for sure as far as comfort. But this one is much too stiff for a back sleeper. Unfortunately for me. I'm 6' tall and the 4" thickness does limit head height. I've been sleeping on a 2.5" mega Thermarest air mattress for years, but I slept terrible on it last summer, so I need to find something better. My lower back isn't the greatest, neither is my LH shoulder, and I'm not exactly young anymore, so I'm primarily a back sleeper now. So I need to keep searching. I'm 6' 165 lbs.