Need reccomendations for mattress topper

When I had a jackknife sofa in my other RV I used One of These to make it flatter then used a foam topper.

Maybe you can cut it to the lengths you need then add the foam topper if needed.

My Class B, Xplorer 230XL, has a permanent bed in the back with a rock hard mattress. I have a bad back. I first put 2-3" thick eggshell foam on top and that helped. 4 or 5 years ago I added 2" of memory foam on top of the eggshell and that is great, very comfortable. I don't know if that would smooth over the valleys in your bed or not.

I can't talk about mattress toppers for the RV but I recently got one for my bed at home and have never slept better. I've got a really bad back and neck and the topper I got is a godsend https://www.amazon.com/gp/product/B00PH8ONBM/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1 along with a pillow Sleep Innovations Contour Memory Foam Pillow, Standard Size. Both are on a 2 year old Sealey Mattress that I thought was very supportive before I got the topper.
P.S. I cut and pasted this from an earlier reply to a different post and have since purchased another specifically for my RV jackknife sofa and the results were the same. Yes it fills in the gaps between cushions very well.

Deb and Ed M wrote:
I always had luck at JC Penney, using their Foam Mattress Toppers. I would avoid using anything that calls itself "memory foam", that tends to be really squishy. The biggest question is where to store the mattress pad while you're using the dinette to eat?

Another thought: I slept on the dinette in our pop-up truck camper. I bought the thickest yoga mat I could find on Amazon (about $17 for a 5/8" thick mat) - it was quite firm and comfy; and rolled back up into a cylinder when done. They are only 22 - 24" wide, so you'd want two....

Sorry - I forgot to add that we keep the bed as a bed fulltime. So won't need to store the topper.

Thanks for the advice about memory foam. We really know nothing about these things...

I always had luck at JC Penney, using their Foam Mattress Toppers. I would avoid using anything that calls itself "memory foam", that tends to be really squishy. The biggest question is where to store the mattress pad while you're using the dinette to eat?

Another thought: I slept on the dinette in our pop-up truck camper. I bought the thickest yoga mat I could find on Amazon (about $17 for a 5/8" thick mat) - it was quite firm and comfy; and rolled back up into a cylinder when done. They are only 22 - 24" wide, so you'd want two....