Following are pictures of the battery installation, including development of the battery racks, deconstruction of the trunk and back seat, and set up of the battery charger and regulators.

Trunk before deconstruction. This is pretty much what the trunk looked like at the beginning, with no carpet and the spare tire removed.
. . .and this is what it looked like with the sheet metal removed! This was the first cut, just to remove the deep drawn sheet metal that used to hold the spare tire.
Mockup of initial design for sheet metal box. This would have been a cleaner installation than the welded angle iron framwork I used, but this approach would require tools that I didn't have.
Trunk with perimeter frame welded in. I added some vertical supports for the frame at the back of the car and cleaned up the surrounding metal for painting.
Trunk battery box. Two rows of batteries will fit - four in front, and five across the back row. Flat stock is welded in place so that the all-thread can hold each battery through the center.
. . .checking with a test battery for size:
Verifying fit of trunk battery box frame:
Battery box. . .installed!:
First idea for back seat battery box. This approach would allow for eight batteries across the width of the car.
Here I'm checking to make sure I can still put the driver's seat back. It's a little tight! After this look, I decided to modify the floor pan enough to keep all the battery tops below the level of the trunk area shown in the background.
This shows the back seat area with most of the soundproofing removed:
A close-up view of the back seat area on the passenger side. You can see where I've marked the area where some cutting is required to get the batteries to sit level.
This shows the newly welded-in material behind the driver's seat:
And now the other side is cut out and ready for new sheet metal to be welded in. You can see the hand brake lines to the rear wheels and the input flange to the differential.
This view from the passenger door shows the new sheet metal floor for the rear battery box area.
Close up of the rear battery box floor:
Many more pictures are on the way. Keep checking back!