Take a hard look at the Tundra Tarp from Cooke Custom Sewing at http://www.cookecustomsewing.com/tundratarp.htm .

These tarps are top quality and used & recommended by many Boundary Waters Canoe Area trippers. Favorite sizes/types include the 10'x10' and the 10'x12' of the 1.5 oz variety.

If you get it, please don't just stuff it in a bag to rot there. Use it and enjoy it.

I'd LOVE to get one of their Leans shown at http://www.cookecustomsewing.com/leans.htm , but the budget (and wife) won't allow it.