Hey Mark. Off topic but one of the previous owners of your wagon from Auzzy land was asking about your wagon on facebook. I sent him the link to ratsun.
I'm sure he is gonna be surprised how badass your wagon is now.
You are not alone. But I think your right it's a Calif problem. When I was in Arizona I put gas in without any issues. And your idea to fill from inside is not a terrible idea. I did it for quite a while before I put in the wood floor.