Jeff,
I'm growing dioscorea batatas in Denver (zone 5). From what I've read, it can't survive below a zone 5 winter, but you can get a good crop in one season.
After germinating and growing them up a little, I transplanted them into apx. 3 gallon pots and put them around a tree to grow up into. We're on solid clay here - picture daikon radishes growing out of the ground instead of into it, so I figured that taking the
root out of a pot would be a lot easier than digging. I did some research on them and the first year they will produce a very nice size root that stores well. You can cut off the top of the root and replant it in the spring. This method won't get you the HUGE
roots, but it may still be worthwhile. I just read today that someone harvested the aerial tubers and ate them like new potatoes. Maybe I'll just bring a few potted ones into the garage to winter over and see what happens....
This is the second year that I've grown them and the first year to try this method. I hope it works well. The first year was in a
raised bed near the porch and the poor thing got sunburned here in Denver, which is why I'm trying the partial shade under a tree method. I'd be interested in your results also.