I wonder how its harvested in south america. They would be be the experts in small acreage quinoa production.
I saw a quinoa field trial last year done by a seed company here in eastern washington. They were finding threre's zillion strains of quinoa with different growth characteristics. They were searching for one that germinates well, is bushy enough to outcompete other plants, doesn't get too tall so it can be ran through a standard combine harvester, and matures before frost.
There should be a variety that works well with garden techniques.