400 miles is nothing in the American West
Absolutely. I recently did 2500 miles in eight days, meandering about and enjoying the scenery. My longest day was 670 miles, because I had an appointment to see an aeroplane the next day! 400 miles is a comfortable day trip.
I'm in Santa Monica at the moment and I was planning to go to Reno (470 miles), but unfortunately a business trip has scuppered my plans. Plan B is a trip to Oshkosh next year for the 60th anniversary of the Chipmunk!