For two years we had a king size 4" foam mattress and microfibre mattress topper with insulation and compact foam on the bed base, but recently modified it.
We cut our mattress down to a queen size, added an eggshell topper, then a microfibre mattress topper, all of which now fit in the mattress cover, making it into a 7" mattress and it`s very ,very comfortable.
Sheets and a king size doona cover which I sewed up on the sides to make an insert to fit a queen doona giving me enough cover to tuck in so Frank doesn`t pinch it all.
In summer we just use the cover only, if needed and if really cold we have an opened winter weight sleeping bag thrown on top.
Robyn