I finally chose a location for the test battery, in the rear seat area.  I was unhappy with the height and rearward weight of the battery when mounted in the trunk.  I used the rear seatbelt mounts and vertical rear footwell kick panel to mount a 3/4in square tube battery subframe. 

The car was weighed with motor, controller, and existing BMW trans/diff drivetrain with no battery, here are the results:

Mounted on top of that is a 3/16in aluminum plate where the batteries mount via threaded rod in the batteries integrated mounting locations.  On top of the battery I temporarily made a condensed wiring layout for the charger, battery management system, and dc high voltage to dc low(13.8v) converter.  Connecting those components together are fuse blocks, contactors and screw terminals.  All connections are crimped with adhesive heat shrink.  

This is a test fit, a future fit of these components will involve a sealed enclosure.  To keep the enclosure low profile the components currently mounted on top of the battery will be positioned either in the trunk or under the battery below where the rear seat previously was.