Where are you planning to "stuff" the extra drop needed until the bed side(s) are removed?
That extra drop either needs to be able to be tucked between the mattress and the sides or it will be puddled on top of the bed
I understand what you are saying, and correct me if I'm wrong, but I thought the drop for the 3-sided configuration should be longer so that when the side is removed, the original drop would then be evened out. Is that faulty thinking?