Thanks Bob. I'll see how it goes once we fully insulate and and cover the walls. The added board may be the way to go, as I foresee some troubles tucking the cover into the frame slot. I built the frame planning to do so, but things change...
We patched the upper row of attaching straps stitching today. Wanted to finish the lower patches as well, but before we could untuck the roof cover (had to lift it and tuck it up to get to the upper straps, then we wanted to get the adhesive couple hours to set without moving the tarp and thus warping it) the temperature started falling to freeze again and we had to stop it, as the adhesive should not be used in freeze. It may remain cold in the following days, perhaps weeks. If so, we plan to use gorilla tape for temporary patches on the lower stitching and do proper patches later, when the weather warms up. The lower stitching can be reached simply with ladder, no need to move the roof tarp.
So, if things go well, we may actually insulate the roof tomorrow!
Also, the door has the outer side painted and dry. I left the inner side with base paint only, as I'll likely be adding some other wooden parts to it and would need to sand the paint off anyway. Hope to post pics of the door tomorrow.
Here's a picture from today's patching.