Theft-proofing a convertible with no steering lock

"Chain it to a building" reminds me of the Dart pulling a small church in Steve Martins - The Jerk :)

When I drive my 67 on vacation like to the beach, I'll have 2 options for parking. Rather than leave it behind the motel, I'll watch for the spot nearest to the sidewalk out front to come open and grab that spot. Afterwards the local police and every Joe Public with or without a camera is watching it for me.