I think it would be hard to stay in motels and eat in diners for $60 per day average. Much of the way you will be able to find rooms in the $40-70 range, but at some places you may find nothing under $100.

If you camp at least half the time and watch your pennies it might be do able. If you were splitting the cost of the room with someone you could probably also keep it to $60 or less on average.

If you just want to get a room once in a while and aren't extravagant with the meals or drink, $60 per day is probably fine.