Yes, I just tried this. Aluminum foil does block the key signal (as does a metal canister).I don't think so, it was designed that way. Have you tried wrapping the key in aluminum foil....maybe it will block the signal?
The other idea, you can hide your key on top of one of the wheels (assuming nobody see you do it)!
I think a good solution is to wrap the smart key in metal foil, and place/hide the wrapped key somewhere in the car when you go to the beach. Then use the manual metal part of the key to unlock the door when you return from the beach.
That is my plan, anyway... (I think it is safer than hiding the key on top of a wheel.) Thanks for the discussion.