How can I mount screening in front of my Prius?

Planning for drive to Alaska next summer and want to install a large screen just in front of front bumper with enough height to protect windshield from rocks thrown up on the gravel sections of the road. I can weld a frame (or use a window screen frame), but I need ideas on how to affix it to the front of the car? Are there solid attach points I can use? Other ideas?

 

Ok, I will try to extend those out to support a cross-bar to which I will attach the screen frame. I think adding side braces to the bolts underneath the corners of the bumper would add necessary rigidity. Need to ptototype this, and thanks for the idea.