My spa is 11' by 14' at its longest and widest points and it is somewhat kidney shaped. There is a handrail reaching in lower than the surrounding deck level and there is a rock waterfall. These present a bit of a challenge for selecting a cover. I have a small dog that I would be worried would mistake a floating cover for a solid surface and drown. So, I need a cover that can be cut to fit and be secured somehow so it would hold a small dog, just 12 pounds. Thanks for any suggestions.