I keep keys/permits/wallet in day pack in waterproof first aid kit. Pack holds my rain suit as well.
Pack will float (I checked) and I keep it a long way from food pack.
Ran into a couple at the start of a trip into Beaverhouse. They were frantically tearing thru their gear looking for car keys ;D

At the point it was getting nasty until the man remembered he had put them from pack into pocket before leaving camp that morning.

You don't want to be looking for car keys at end of trip. I also keep spare set in magnetic case hidden on vehicle. Not a bad idea just in case.