Not so long ago you could carry your car keys in your PFD pocket and not have to worry about things like remote central locking, immobiliser coding or anything else. If your key got wet it didn’t really matter. Things are different now.
You therefore have three viable options:
1. Hide the keys on, in, under or near the car. Super risky and the insurance company won’t like it.
2. Carry them in a nice waterproof case in your boat. Good cases are easy to find and it’s easy to store them in your boat. However lose the boat and you’ll lose the keys.
3. Carry them with you.
After finally finding a low bulk waterproof solution that would allow me to carry my keys within my PFD I have went with option 3.