To determine which sheet size to select for oddly shaped mattresses, make sure the sheet length and width are the same or smaller than your measurements. For diamond shapes, you can order a sheet that is slightly smaller than the maximum width where it juts out in the middle, it will just have slightly less fabric depth in that spot. For individual V Berth boat cushions, our Twin XL Sheet Size fits nicely for lengths up to 80" and cinches to fit smaller widths and lengths.
RV Mattress Guide:
RV Bunk and Twin Mattress Sizes - Order our Cinching Twin XL Size
RV 3/4 Full, Full, Full XL and Short Queen Sizes - Order our Cinching Queen Size
RV Short King and RV King Sizes - Order our Cinching King Size