Our new 37&1/4 came with a poor king size mattress. We are thinking about getting a sleep number mattress like the one we have in the stick house but ours in the house is a different size and does not have radius corners the question I have is it a must for the radius corners. I see camping world sells the size needed for the 5'er both ways square and rounded. And is the one camping world sells as good as the one we bought for the stick house.