It kinda saying two different things. It saying they are legal then it says about the bait. I was thinking about using the whole in the board with the coilspring method. But i would be willing to bet that would be illegal.
I use a paper cup over the traps...not really to make the bait invisible from the air, but for a visual attraction. I never considered it, but I suppose it takes care of that problem. Coon will flip the cup off.
Not real sure to answer your question furcatcher. I thought of this before. Personally I stick with a tin can drill a small hole in the side near the top of the can. With about 6 inches of wire, tie the can to your trap chain. Acts as a nice visual,keeps the mice out, hides the bait from the air and nothihng will carry it off. Spray paint it white if you wish .. this would solve your problem. Just my 2 cents.