I run mine to the trunk latch bolt. Worked fine for years.

Always run a negative wire smaller than the positive wire running to the front. If the positive wire grounds and they are the same size it will burn both wires sparking a fire along the whole car. If the ground is smaller, only the ground burns and it will be limited to the trunk. Kinda like an emergency fuse. I suggest at least 2 sizes smaller.

For those who think it won't happen it did to me. Trunk filled with smoke but the car was OK. There are other methods that help prevent it but even with those in place this method costs nothing to do. One method is to put a solenoid on the positive going to the starter in the trunk so the main battery cable is not live all the time but it still has to go live to crank. If it goes live to turn the starter and the positive wire is grounded it will still burn the car.