the last two 5er's have had the same 10" memory foam King mattress in them...
I told the dealer not to even take the plastic off the redwoods mattress and it is safely stored in our storage building
yes, it is a tight turn into the 38gk's door, but we went into the living room first, then back up the stairs and we have the same mattress at home and on the road... makes for an easy adjustment period