I got a little more time to work on the front rack, welding the cross-members in to the base. This picture shows 8 batteries nestled in the base, a perfect fit:
Here is the same rack, propped approximately in its final location. Next up - welding the supports from box tubing (1 1/2 inch size, with 3/16 inch walls). The rack will bolt on to the supports, and the supports will bolt in to the frame rail. I'm considering making the remainder of the rack a separate bolt-on piece so that it is not so heavy.
Here is what it is supposed to look like when all is said and done - from Google Sketchup: