You can make your own cable using sufficient gauge (for a 700w, 8ga or lower) wire and ring connectors. The only thing with putting it under the seat is that they can be noisy at times (when very hot or very cold). I could hear my inverter turn on on the cold days under the floor of my trunk (which is really the ideal spot for such a setup). Also, if you permanently install it under your seat, youll have the power cord running from the cabin to the trunk. Temporarily, I dont see why not (heh, i had wires coming from under the hood, out side of the car, in through the door and down the middle of the cabin to the back seat for a few weeks ). and unless you're trying to run an electric oven off the inverter for a few hours, I dont see the inverter getting even close to hot enough to melt plastic.