North Slope Alaska worker travels to and from home every 3 to 4 weeks. They live 1 hour away from the airport. They buy their own food when waiting for plane to take off or if the plane is delayed. They have to travel back home if flight is canceled by weather. On their down time at their job location can they claim per-deim since they are not working. They are provided with meals if they want and lodging for the time they are there.
You can deduct expenses for travel from your home and a temporary work site outside the metropolitan area where you live. Temporary means you are not expected to be there more than a year. Also, if the work site is your regular work site (more than a year) but it is remote and your family would not be able to reasonably live there, then the travel is deductible.
The down time at the job location would not be deducted from the days counted for per diem meals. You can use the per diem meal allowance but not the lodging per diem. The IRS does not specifically mention that you "can't" use the meal allowance if a free meal is offered but not accepted. Here is a link to the GSA website Per diem rates lookup. Click this link to read more: Per diem FAQs