Fwiw we found the stock 7" foam mattress in our '16 FC to be hot and not very supportive (you'd sink in, then it was hard as a rock.)
We recently bought a three layer 11" "Denver Mattress" Supreme. It sleeps much better, and does not cause the aches and pains we had before. We really like it so far.
Might be an option to look into if the coil option does not work out.
2016 30' Flying Cloud / 2016 Ram 2500 Diesel 4x4
“Character is doing the right thing when nobody’s looking. There are too many people who think that the only thing that’s right is to get by, and the only thing that’s wrong is to get caught.” - J.C. Watts Jr.