My zip is 98006.
I can get you some exact measurements tomorrow. The issue I have is that the back seat is slanted rearward as it gets near the top and takes away some of the room. For example, I think 26" deep works at the bottom but maybe only 22" at the top depending on height (these are just examples ... not the actual measurements). The rear door is also slanted in so I need to account for it.
Are the boxes insulated at all?