I do know one thing. If you intend to stay under a tarp in 40-50 MPH winds you better have some serious "tarp" experience. I could probably manage but I will have to say that if I had my choice, I would chose to do some thing else. The tents that you said you guys had would be a much better choice than a tarp in that kind of weather with those high winds...You could stake a tarp down but it may well turn out to be a work in progress, and I do mean throughout the night. Assign some one through the night to keep all the guy lines tight...sabre11004...