Now I just hope that it will all fit on the van as planned, i was going to move the regulator forward as well to get the box back as far as i could. There is room according to the tape measure but nothing beats the real world test. I didn't want to put the bottles in the box if i could avoid it.
for what it's worth, when I was figuring mine out, this is what I measured (without relocating the regulator, so the box can still push back a little)