The silicone is an idea I had not thought of. I've been using out of date Resin from work which is probably better, but not very many people have access to it and until it dries it is classified as a hazardous material.
I've tried to use the wiring method in the above diagram, but I found if you have one bad connection you throw off all the heating elements after it. I found buying a seperate light duty 6' extension cord for each sheet of flex watt and then plugging them into a power strip that is plugged into the T-stat is the most versital way of doing it. Each cord only costs around a buck fifty at Lowes, but if you are not using tubs in the rack you can unplug then and save the power. With the current cost of electricity you can save the cost of a couple additional power cords by not having to power extra ones all the time! Also energy conservation is eco friendly!