Hi guys, thanks for helping me! I am working on a home project that includes a privacy shade for my backyard. I have a 6'x15' vertical shade attached to two portable posts that are held up right by four legs ("X" shaped footprint). the surface footprint of the legs covers an area of 46"x70". I am trying to figure out how heavy my two posts have to be to keep my vertical shade from tipping over in the wind at 25mph. This will determine what kind of material I use for the post (probably steel) and if needed how heavy of a sand bag I would need to add. I calculated that at 25mph the shade will experience 1.6lb of force per sqft (not sure if this helps, not an engineer or student).