Since only I am posting to this thread, it looks like I'm talking to myself. But that's never stopped me before! :-)

Ok waterproof bag, nikwax proofing. Here's a third solution:
A waterproof breathable bivi bag.
For 110 pounds (which normally translates to 110 dollars) you can get a goretex upper and waterbloc base bag, that weighs only a pound. Made b yTerra Nova. Don't know if that makes exist in the states; but you'll have equivalent bags.
Handy for when you don't hav the room or are too exhausted to erect a tent. Or just want to look at the stars.
The Sock