1. Buying and registering a vehicle. I have been told there are sales tax benefits to be had based on where the vehicle is registered?
Yes certain states don't tax new vehicles: Montana for one. Avoid buying in California for sure. Usually the tax is based on where you register the vehicle. This can be a problem for someone who is a resident of say California or New York since their tax authorities (read inland revenue) will come after people who buy out of their state to avoid taxes. But as a non-resident I don't think this will affect you.
2. Does all the above apply to the fiver too? I.e. Does a fiver have to be registered or is it just the vehicle.
Yes they are registered and need a tag. Again just say no to California. The RV dealer will get you a tag, and charge you for it too.
3. Are there any special licence requirements/limitations based on size or weight of the rig? In the UK a standard car licence is good for vehicles up to a certain weight. After that a special test is needed.
A standard driver license will do.
4. I have read somewhere that certain states have size (or is it weight) restrictions. Does anybody have some kind of guide to these? I would hate to cruise into a state and get pulled for being too long/heavy without realising it.
Should not be a problem.
You do understand that a fifth wheel requires a large and very expensive truck to pull it. Generally a 1 ton pickup from Ford, Dodge or GM, maybe with dual rear wheels for the largest fifth wheels. These trucks will be in the $60,000 to $70,000+ dollar range on the sticker price. That can usually be negotiated downwards but they will be expensive. Also you will need a fifth wheel hitch in the $1000-$1500 range.
Don't buy anything unless you seek advice here after you get more details. Truck and RV salesmen lie frequently.
There is a certain amount of learning involved in driving one of these rigs. The trucks may be over 20 feet long and the fifth wheel can be over 35 feet. Are you sure you would not be better off buying a used Class C like you are thinking about renting?
