Given that there are 33 of them in the country, I would imagine quite difficult. I also wouldn't assume that working for the park service generally is an especially easy job. I've know people who were semi-retired who worked in parks on a part-time basis but I assume you have a lot more flexibility under those circumstances but don't get paid much, if anything.

I'm sure it's a job that many would prefer compared to sitting in an office all day but that doesn't mean it's easy.