Thats an interesting idea. I was trying to get all the bracket/plates in between the batteries to add support but maybe making my own would be easier... I'll have to look into it further.What about an angle iron base and sheet sidewalls as a box for the pack that keeps it all from sagging?
Don't forget the first speedbump could make that thing weigh 5x or more what it does static.
Its actually a 2 seater so rather I'm leaving room for the driver and maybe passengerIf it were me, I'd look at stacking the battery modules over the axle, as far forward as possible, to pull in the polar moment, get some crush space so you're not building an electric Pinto (you're clearly making an effort to leave the back seats open for the kids...), and have a spot for groceries....penalty is c.g. goes up a bit.