Where did you get that info? According to the Surly site, the Cross Check has a 6.6 cm bb drop vs 7 cm drop on the Steamroller. But really, I should think either is plenty high, and one should keep in mind for touring that bb height comes with the cost of a higher center of gravity.

As for the OP, sorry I implied you were new to this -- sounds like you've got a chunk of touring under your belt. If you really like the Steamroller, by all means go for it. Practically speaking for what you described, I think the Cross Check is a much better choice. It's better suited to run some of the load up front, and whatever you choose to mount (I should think fenders at a minimum for the route, even if you're going super-light), it will be easier on the Cross-check. It also has canti studs, which I would employ in your shoes.

In case you haven't already done so, I'd check out some rando rigs for inspiration -- they would suit your packing list and your plans pretty well. Most importantly, make sure to post pics of your bike (loaded!) when you get everything together.