Revisions log for Answer #2238

 My opinion of the project is also rather negative. There are two reasons for this:

1) Despite the patio door and vapor barrier underneath, moisture will slowly creep in. Every time you open the door.

2) As far as your whole philosophy goes, this project is like the proverbial sparrow hunt with guns.

If you need a more permanent (or at least warmer winter) environment for certain things, it's a very good idea to make a small insulated thermal box.