Have any of you have success using recycled Billboards or misprints from that industry.

The most common locally used material is a reinforced vinyl in heavy weight (last time I checked it was 6oz or higher). It is UV resistant, it's tear resistant. Of course you may have a big Budweiser, KFC or Corona print on one side, but I have yet to figure how they are disposing of those materials. I used to work with smaller signage and I have always thought of that material as tougher than the FEMA/Wal-Mart Blue Tarp.