RE: Tree Umbrella....PITA?
They work great. I've used one for over 2 years now. You'll be in the woods while most are back at camp and you'll be surprised how much deer movement there is when it is raining.
One warning though, get one with the wind vents. If you don't have one with wind vents and you get a stiff wind, the thing is likely to invert. I'm talking from experience here.