High tunnel dream

I'm thinking about building a high tunnel. This is my example for myself to look at and decide how I want to build it.
A high tunnel seems to be a good way to be able to extend the growing season by a month or so on either end. This would be like a small 10' by 30' plot covered in plastic in which I could grow long season flowers like lisianthus. Of course, the chances of me building this are slim at this time. But I was thinking of this as a project for next winter. Whatcha think???.