I'm eagerly awaiting your pictures as well.
I'm using cattle panels as a hoop trellis and I have 8 EarthBoxes (next year I will only put 6 in there - or add another panel) in 2 rows that I can easily walk between. It is tall enough to walk under and still reach the veggies. The tromboncino hung down and one was over 4' long. If the tomatoes hadn't been deer lunch and had to start growing all over, they could have climbed over the top and down the other side, as it was, they just reached the highest part of the hoop.
I was thinking of using a plastic greenhouse material that is corregated to turn it into a mini-greenhouse, but the people who sell the plastic didn't think it would work. I think the plastic film would be too difficult for me to use - but it sure would be cheaper. http://www.greenhousecatalog.com
is not far from my Dad's place. He has a small greenhouse made out of this material and I still think it would be perfect.
The cattle pannels are 16' long and I have several of them tied together to make a hoop over tomatoes, cukumbers, and squash. Since stuff is growing outside the trellis/panels, I thought a 20' length of plastic would give things the space they need. The plastic would only be connected to the panels at the bottom. It comes in a continuous roll, cuts easily, and would be easy to take off and store in the summer. We sometimes get snow, but I think most would slide off the top and not collapse it.
Perhaps your pictures would help me explain what I'm trying to do. ;>