At this point I've been reliably deploying these and several other models of surface for a couple days. It's safe to say the problem is fixed, but I'm not confident I know why.
My best guess is I had enabled Randomize GUIDs in Admin Settings -> Image Profile Templates, for the LinuxBlock.
I first tried Standard Partitions while this was enabled, and it's the only thing I can remember that was consistent between when deploy didn't work, and when it did. Everything else I tried didn't correlate, as in, I was having failures and successes with the setting in all states.
I'd still love to understand what was going wrong, if that is possible to discern from the existing evidence, so that I can avoid or fix it in the future.