It seems pretty stiff to me as well. I never spend that much and don't need to resort to begging or dumpster dipping. I do try to avoid staying in expensive campgrounds but don't usually resort to stealth. It isn't too hard to stay for free more than half the time. I find that I can eat at diners once a day or so and only drop $6-8.

A lot depends on your personal choices. I know of folks who managed on $10 per day and others who spend $100.

It is nice to have more than you will need or spend, so I'd set aside $2500 and probably spend less than $2k, but I am fairly frugal and resourceful. If I had to I could get by on a good bit less but don't really want to.

Also remember that you won't be spending on the stuff you would be at home. When looking at the paper trail after one of my trips, my wife commented that since I wasn't buying gasoline for my long commute I was spending less than I did when at home.