Sink covers are a classic “mixed blessing” in an RV because they are nearly useless while preparing food because they totally eliminate access to the sink but may, in fact, almost double your work space (kitchen counter). Cutting larger sink covers in half will allow the cook access to the sink without sacrificing all the surface area plus actually extend the countertop work area—a definite win-win!
Composite covers can be cut using nearly any saw with a carbide blade. I recommend a circular saw because it is easier to keep a straight cut. Use a file to round the sharp edges. After cutting, the two pieces will continue to totally cover the sink if needed, look exactly the same when traveling, and since each piece is smaller, they are easier to remove and handle