[hardk0re]

But you don't need a negative...any metal exposed point on the engine/chassis is as good as ground...

In fact they always recommend you don't connect negative right to the battery when its under the hood, they recommend a chassis point instead. Thats because of explosive gasses from the depleated battery but anyway chassis points are the way to to it. When I did my bat relocate I just had a + up front, along with my + distribution block.