Operation: Tape Measure Assault has successfully annoyed a Subaru, Honda, Toyota, Hyundai and Ford dealer. I also measured a Dodge Caravan because there was one handy.
Conclusion: WHAT THE HELL DO YOU MEAN IT'S TOO BIG FOR A DODGE CARAVAN!? (The Caravan is SUBSTANTIALLY shorter in usable height than the crossovers. I don't get it either.)
Finalists come down to the Ascent and Flex.
The Ascent is almost PRECISELY the correct height in the vertical axis (it's so tight I actually have to go back and measure the curvature of the hatch opening more precisely) and approximately 3 inches too short (I haven't DQ'd it because I forgot to check to see if the second row seats have sliders or recline that can make that up). It does, however, have the distinction of being the only thing besides a minivan that leaves space for the second crate AND still has room for a couple of carryon size bags. Seriously. It is stand-out cavernous once you get inside the hatchway.
The Flex is actually smaller than it looks. It's rear hatch is big enough (and weirdly almost a perfect square). It is substantially narrower than the Ascent, however, and will not fit both crates, meaning the second row passenger seat gets a big metal box bolted into it, making it a less safe place for childrenz.
Advantage (assuming the clearance issues can be resolved): Ascent.
I have also inquired with the crate manufacturer about a custom size that trims off inches to make it fit an Ascent. They build the things to order anyway, I wouldn't think a custom size would be too big a deal.
I've really wanted to like the Flex but it falls short in a lot of aspects. It's also quite old as the last update it saw was 2013 or so. Looks like fun this work...