Temporary waterproofing with tarp for winter

We're doing some renovations and this part involves a small 12*12 outside extension that has a below grade basement/utility room.
The one level extension and roof, which was a kitchen, will be removed, exposing the basement to the elements. This area will eventually become a deck with low slope roof as per my other post:
Mini low slope roof

Because of the other renovation work and needing to wait until a bit of brick work is done where the wall meets the floor (now to be outside roof), I cannot permanently waterproof it with membrane.
So, I am wondering how to temporarily waterproof it until spring.
It would be covered with snow during the winter that I can shovel off if needed.

Do you think a big tarp at 5mil or 10mil would do the job? I can further protect the tarp from foot traffic with some junk exterior plywood on the top. The difficult part is waterproofing where it joins the house wall or what will eventually be a patio door.

 

Tarps can keep out much of the water but they always seem to have pinhole leaks that let a bit through especially with puddling on a flat surface. I've had OK results putting down an old tarp, old carpet or anything as a protective layer. Then a sheet of heavy duty plastic (6 mil or heavier). Then a good tarp on top to help protect from sunlight and the weather. And finally boards laid on top to hold it all down and prevent flapping in the wind. Better would be if you can somehow create pitch or slope so water runs off.