Hi Larry,
I don't trust the 20 to 50 minute drive home to dry out those quarters. My White car only gets a tiny bit of splash water but I've always suspected a tiny leak on the right side of my Red car. I've never been able to find it though. Anyway, at the end of a days run, and before driving home, I always run some quarter folded paper towels down there to be sure they are dry and I let the drive home absolutely finish the job. By the way, even if your feed through pipe from the front trunk to the back is open and working correctly, the pipe doesn't get close enough to the trunk floor to completely drain that area. When I get home I run another towel or two down there with an extension handle (Ace Hardware) to get any moisture out of there too. This problem is why you see most Amphicars have some, or a lot, of rust damage down there, and it's easy to avoid. Just a bit of after run maintenance guys. These cars are 50 years old and can use all the extra help we can give them.
John Friese
67 White
67 Red