I am moving to the desert in Arizona. Due to a health condition I will sleep slightly elevated… We are wanting to convert two twin XL onto a king foundation. My side using an under the mattress wedge. We have no wish to buy an adjustable frame. We are looking for advice on a cooling , medium-firm mattress. I’m a side sleeper and my wife is a back- stomach sleeper. We like our present foam gel bed and look to stay away from a traditional spring setup. Thanks for any insight y’all can provide.