I was poking around the Armbian forum to see if they’d made any progress with the Tinker Board, and learned that they didn’t have one, and they’re pretty busy anyway with the small mountain of other devices they support. They do, however, support the MiQi, another RK3288 Raspberry Pi look-alike. So I tried the image, with no luck. The Tinker Board, it would seem, is a lot more inflexible when it comes to booting. After changing U-Boot sources, getting advice from an apparent SoC engineer at http://tinkerboarding.co.uk/, and changing a filename or two, I was able to boot Armbian on the Tinker Board with a full Ubuntu Xenial desktop.
https://forum.armbian.com/index.php?/topic/3327-asus-tinkerboard
Considering the level of polish on the ASUS images, this version is a breath of fresh air, supporting some hardware acceleration/etc.
I’m waiting to see what the good folks at Armbian have to say, any luck they’ll roll out an official image.