It appears from the product photos and the unboxing video that there are two foam blocks of equal length occupying the third card tray in the base game as it is shipped (since a tray seems to hold ~500 unsleeved cards and there are three trays). One of those would presumably be useful (and not mere disposable packaging) for those people who have some (but not all) of the expansions, to help the cards can stand up in the trays at a good angle. Yet a 50/50 split is not optimal! A 1/3-2/3 split actually provides for more possibilities where the cards don't fall down. Of course, this comment comes far too late: first campaign backers already have their first box, and the contents for rest of us are certainly already fixed due to schedule. So forget that.
But! The white box will have roughly 500 cards in it, and thus, presumably, two empty trays. May I humbly suggest that the empty trays in the white box be padded not with 50/50 blocks but with 75/25 ones? After the second kickstarter there will probably be much more variety in the card sets that people own, and this will give everyone flexibility in how to arrange themselves!
(PS Other, more mathematically interesting, solutions are obviously possible, especially if you pad with combinations of blocks, but 75/25 is nice and simple, lets both white trays be padded the same way, and doesn't involve any blocks that are tiny.)
