It depends upon what you mean by "making" the corner bed.
We have a 3" foam mattress we bought of just the right stiffness covering our corner bed - we cut the corner off the rectangular piece of the foam to make it exactly match the corner mattress under it that came with the motorhome. The 11 year old corner mattress that Winnebago delivered with the motorhome has a nicely fitted and color coordinated heavy mattress cover on it. This corner mattress has not broken down in 11 years and we've never washed it's stock mattress cover - no need to wash the original cover as it's always been covered with the 3" piece of foam on top if it.
We have a fitted sheet that exactly fits the piece of foam. The DW sleeps directly on the fitted sheet with a comforter on top of her. There is nothing to "make up". We just pull this fitted sheet off the foam piece periodically and throw it in the washer.
I know of no other design way to have a ready-to-use permanent floor level queen bed in a 24 foot motorhome with no slides without it being a bed in the corner. For us compact easy to heat, cool, and clean smallness along with complete self-containment was highest priority for our camping style.