Two things to keep in mind since you are in CA.
The first was mentioned and that was insurance,
The second is CVRA. The F450 would definitely fall into that and they are illegal to drive in CA without the sticker on the door unless you are hooked up to an RV trailer and never plan to unhook and drive bobtail. The new 1 ton duallies from any manufacturer are the same way. They all have an unladen weight of over 8k and a GVWR of over 11,500k. You need to declare your GVW and run the appropriate sticker on the bottom of the doors. If you never plan to unhook from your RV, you don't have to worry about it. If you do plan on driving your new truck around town without the trailer attached you need to make sure you have it registered appropriately.
The one way to get around it is to take your new truck and declare its never going to weigh more than 10k. Then you do not have to pay the CVRA fee every year and run the stickers on the doors. God forbid that you ever run to Lowes and put a pallet or two of pavers in the bed of the truck. If you get caught over the weight you have declared it is not going to be cheap.