For riding in California, trailer towing is avoided by those who can. CA has a ridiculous 55 mph law for trailer towing, and if it's snowing at all or there's any snow on the road, you have to chain up. But if you're just carrying your sled in the back of your truck, none of that applies.
That's why a lot of people are putting flatbeds on their trucks instead, since that way you can carry two sleds pretty easily, and without being as top-heavy as with a sled deck.
As far as sticking out goes, the law I saw is that if you stick out 4' or more, you need a red flag.
Rob