i would suggest a slope to the roof for rain and snow
I had thought that I might make a small hole in the middle of the two roof sections to allow the rain to drain into the tent and put a plant pot or saucer on the ground under the holes to prevent erosion and cause the falling water to splash around.
I hadn't thought about snow!
also would need securing against wind damage.
My plan for fixing the poly to the frame was to reenforce the poly locally with duct tape (orange) and use 10mm or 12mm wide cable ties (black) fed through slits in the poly/duct tape:
(See attached image. (Can you inline images here?)).
The solid dark grey rod is 10mm rebar at the bottom of the 4 sides. Its weight will hold the side in place in most conditions, but I can add short bungy straps to hold it down and against the uprights in windy conditions.
The idea is that I can lift the sides and ends up for access and drop them down when I'm done.
allow for ventilation in warm weather and extra watering no rain able to get in.
I think this is covered above?