If you itemize your deductions, the IRS has a table to determine your state and local sales taxes, but you are allowed to add anything like a motorhome that is large and unusual. The short answer - yes.
2001 Newell #579
tow a 2011 Honda Odyssey
1935 Mercedes 500K replica
Check with your own state. Some states do allow you to claim or write off local vehicle registration but it may or may not make any difference depending whether you have a business or file as an individual.
Yes for now. The sales tax is part of Schedule A line 5 of the form. I think you can use either sales tax paid or state tax withheld but not both. I suspect the sales tax option is for tax payers from states that do not have income tax and rely on sales taxes such as Texas, Florida and Tennessee to fund the state.
Also check for potential deductions for state and local personal property tax on the coach and interest if you financed the purchase. If you are not sure check with a licensed tax preparer. The government want’s their tribute and has rather nasty ways of getting it from you. Just ask Al Capone.