fabric rather than film
* The tenting can make things get overheated if you leave it on when temps get over 45 F. We lost an SFG box of herbs to…I guess you could call it cooking. This was with very thin plastic (painters drop-cloths from Lowes). It might be even worse with thicker plastic, or glass.
* The plastic also can cause the inside to be overly moist. We lost one SFG box of veggies to mold due to the moisture. Water tented veggies sparsely as they recycle water very efficiently. Open them to breathe whenever temps make it possible.
How about using a fabric like Agribon?
I think it would help with your overheating and definitely help with the moisture situation.
Another possibility is Covertan Pro 17.