Can I deduct or get a credit for customs duty paid in another country?

You can't take a foreign tax credit.  In order to qualify for the credit, the foreign tax must be an income tax.

https://www.irs.gov/individuals/international-taxpayers/foreign-taxes-that-qualify-for-the-foreign-tax-credit

but can it be deducted if I'm itemizing? 

Customs duties are not deductible as a personal expense.  However, if the vehicle is used in your business, the shipping charges would be deductible if they meet the IRS criteria of "necessary and ordinary".  Under IRS regulations, a business may deduct any expenses that are "necessary and ordinary" for business functions. To meet the criterion of ordinary and necessary, an expense must be common and appropriate for the type of business claiming the expense.