I was having a geek moment deciding how to mount the batteries.  I moved the AL plate for the back to the top. 

It was a little too long for the bottom or to be cut without dragging out my table saw, and so I started to invent other reasons to move it.. like then entire bottom could then be a lighted panel.

I decided to place the batteries as far apart as possible.

(this shot was actually stupidly dangerous as I had not taped the terminals and just balanced them there for the shot)

The reasoning is that for the same mass, spreading them apart will maximize the moment of inertia of the platform along the long axis of the board.  

The figure skater in the triple axle now has Hellboy hands.

This should enhance stability.