State doesn't matter... Both state law as well as federal USCG regs do not say anything about this. The trick is the UL certification. Most inflatables are specifically certified when worn only, and have no type rating when not worn. In other words, you can't call it a life jacket if it isn't attached to you. They are also not type certified for anyone under 16, so again, you can't call it a life jacket if a 15 year old one is wearing it, they have a collection of rubber and plastic parts that might save their life, but not a certified life jacket.
Now do your local guys know the ins and outs of these regulations, probably not, but it doesn't change the legality of it. You need UL certified life jackets on board, which an inflatable without a person attached is not.
The other thing to keep in mind, a lot of inflatables will not inflate if you toss them into the water. The trigger has to be more than 4 inches under water, and most of the time they will float, at least for a while, closer to the surface.
Just speculating here, but I'm guessing the 'only while worn' certification is because of the difficulty in getting an inflatable on while in the water. I have to imagine it would be tough to get it on completely, and that is assuming it actually inflated.