I have such a project in progress.
I intend to build a shooting house, but ran out out of time to get it completed for this season. I have built a 6'x6' platform on 4-foot legs atop some deck blocks which raises the whole thing to about five feet. By next year this will be the floor of my shooting house.
This year I am putting a pop-up blind onto the platform. I have attached both screw eyes and screw hooks for anchoring. The screw hooks will be used to hook the little loops in the bottom edge of the blind to hold it down and spread. The screw eyes will be used for attaching the tie-downs since they have loops. I'll let you know how this works. :-)
4x4 is too small for a pop-up. 6x6 is just big enough.