Base-camp for Mt. Humphreys, AZ peak bag?

The only place I can think of that is right below the trail through Snow Bowl, which is where the trail to the peak starts, (Humphreys Summit Trail #151 ) is Harts Meadow. And that is tricky cause much of it is private but you can find some USFS land intermixed just below the ski slopes, it will just make the hike a bit longer. You will want to drive in on the FS 151 DIRT road off the 180 north out of flagstaff and find any camp spot to the right before the harts prairie nature preserve. Or you could stay there, they do rent guest cabins.
I've hunted and hiked in the area for 35 years but do not live there.

This is from a report.

Coconino FS Reports This steep mountain trail leads to the highest point in Arizona. If you consider it merely as a means to that end, however, you'll miss much of the reason to come here. Along its 4.5 mile course, a thriving alpine forest streaked with huge rock slides and avalanche tracks hugs the mountain's slopes. Scenic Hart Prairie stretches out the base of the incline and the Grand Canyon is easily visible on the horizon.

As the elevation increases, trailside vegetation shows more and more evidence of the extreme harshness of this environment. Near tree line what's left of the forest consists entirely of bristlecone pines bent and twisted by wind and frost. This hardy tree manages to live one of the longest lives on earth in one of the planet's most inhospitable environments. Above tree line the only plants that can survive are small tundra shrubs and wildflowers that huddle for shelter among the rocks. Some are found nowhere else in the world. Overhead, above Arizona's highest ridge, white-throated swifts dive and flash like miniature fighter planes as they feed on nearly invisible insects borne on the wind.

Humphreys Trail is steep and long and extremely rocky in its higher reaches. Above treeline it exposes you completely to the whims of nature. Here it may snow during any month of the year. In late summer monsoon storms can set the high country snapping with lightning. Be prepared to turn around and head for lower ground if a thunderstorm is brewing!

There are first-come-first-served car camping spots along the road up to the trailhead. Off-season, many of these spots would be available.

Most people do Humphreys as a day hike, as the distance/elevation gain are not extreme.

Unless you get altitude sickness, you should not have too much trouble on the hike, even if you aren't in perfect shape (just start early and take it slow!). The trail to Humphreys is quite good, easy to follow, with lots of switchbacks to help you get up there, and it's a very popular trail (highest peak in the state).

If you can't tolerate altitude, or if you run into bad weather, it could be a rough hike, but in those cases, camping part way up wouldn't help…