Hi there. Anyone have any ideas how I might secure the center poles under the tarp to keep it from getting kick or bumped and preventit from falling down? I've got a total of 10 collapsable poles I made from electrical conduit, 8 of which I plan to use one the perimeter. The other 2 I plan to put tennis balls on top and use them to prop up the center like a circus tent. These are the ones I need to protect from getting kicked or bumped.