Chuck,
There are a number of people looking for alternatives for mounting dual batteries. I was forced to locate mine in the rear over the rear wheels (a good place to mount them for weight distribution) so I could make room for my air compressor. The only negative side to mounting it in the bumper is if an accident occurs. It puts the battery in harms way and creates a potential fire hazard if it should short in an accident. I wish Nissan gave us more room under the hood. Making stuff fit can be quite a trick.