My husband and I are driving just over 1600 miles in just under 3 days.... and then rest for 3 days and back the 1600 miles in another 3 days... How long do you all advise we drive each day?? and do you maybe advise 4 hours shifts, or do you think it is best to drive until tired then switch? The longest trip we have done before now was a 7 hour trip in one shot... Thanks all!!!! :)