This works very well for the run. Although I didn't have exactly what you have stated, I did something very similar that many people that I've seen here on BYC have done also. I have a hard roof (decking and shingles) over our main run and I put clear visqueen (plastic sheeting) on all sides with plastic lattice on top of that to keep the wind from tearing it off. The result was a green house type of effect. During the day it was always about 20 degrees warmer in the run than it was outside. I did leave a small space at each end at the top for ventalation. It worked very well and my girls spent alot more time out in their run than previous winters. I think that the greenhouse type run would work very well for you!
