Scott
Insurance is pretty cheap.
$100 a year for $20,000.
I hate to lay this on you but you probably have the rarest collection of the first 17 known to the Harbour Light collecting world. I doubt that anyone has matching numbers for the first 17. In the early years there was no consistency with what dealers got what number. It was probably around 95 or 96 when the low numbers started to become regulated. Even then some scattered numbers would show up.

At the least you should have them insured. Probably the best would have them boxed and the standard Malaysian set displayed instead of them. But A lot of collectors would disagree with me. Many feel, why have them if you cant see them. I am glad you didn’t put the quake clay under them. It damages their felt. Maybe there is something else out their for earthquake proofing that won't damge your lighthouses. But I havn't heard of it.