I would like to build a 12'X 36'high tunnel/cold frame for next spring out of 1 1/2 inch plastic pipe. I only need it from the middle of April on, so snow should not be a problem. After i have sold my bedding plants out of it I would like to plant a crop for fall markets. The plastic will come off about the end of October. Has anyone tried something like this, and how did it work?