We use a 4"and a 2" memory foam on top of our California king RV mattress, and love. Having the AC on above the bed, and I sleep like a baby. The stick and brick has the same setup, w/o the AC unit. ( trying to figure a way to get a Roof top AC unit in my bed room. Ya I don't like a dead quite room, growing up it was railroad, or highways in the back yard. I can sleep through most anything, except dead silents.
Stay away from the cheap foams (ones with egg crate patterns, you not getting the full support from them.
We bought ours ( they are Serta's ) and were from purchased from Overstock.com
Steve & Linda
Son married (1 DIL, 3 granddaughters 1 grandson)
Daughter Married.
Miami Co. Kansas
2004 F350 CC dually 8ft bed 6.0 PSD
2009 Bighorn 3670RL
B&W under bed hitch with 18k companion hitch