I love how you post something and then everybody loves to twist it. I commented on 45 foot motorhomes in California. I commented on more than just the restricted sections of the PHS. I said I personally would not get one because I don't want all the added restrictions. No place did the OP say I'd like opinion about restrictions in every state other than California.
This is a link to the California rules on motorhomes over 40 foot in length:
45 foot motorhome rules for California I'd be willing to bet that many other states have similar restrictions.
Note, on the Interstate system 45 foot is completely legal. But once you leave the Interstate you fall under local and/or state rules. Note how long this list of rules is and how it even refers you to the rules of others. And if you do bring your 45 foot motorhome to California every one of these rules applies to you except for the Drivers License requirement. As long as you're legal in your home state you don't need the Class B license.