I think I read somewhere that you can rent one for a vacation or weekend use now.
Smoke
The National Forests in Idaho and Montana have lookout towers among their pools of rentals available. Some of them are quite remote and their very nature would dovetail nicely with a WTW-style trip, where one you're automatically going to have water, supplies, and, ahem, a familiarity with cat-holes and their uses upon arrival. There are some online listings through a lookout tower forum I recall reading (folks will join up on just about any common interest, won't they?), and some of the NF websites I'm used to consulting show the lookouts among their rentals.
And speaking of other rentals, the so-called "work crew cabins" might be of interest to some. The ones I'm familiar with are in Montana and they make a great place to bunk out, as that's what they were designed and built for. Years ago, USFS work crews would overnight in small cabins having 4 to 6 bunks rather than ride/drive all the way back to town each evening. Nowadays, pickups take the crews home each night, and the cabins are maintained as rentals. Some are XC-ski or snowmobile-access only in winter. All come equipped with Coleman stoves, fuel, cookware, utensils, and firewood (and a woodstove). All have a hand-pump well and an outhouse. The lookouts and the work crew cabins generally rent for $15-20/night. They're easy to book during the week and they make it possible to, for example, fly to Missoula, MT with only your flyrod, waders, and clothing, rent a car/SUV, buy a big cooler, load up at the grocery store, and drive up Rock Creek Canyon to the Stony Creek cabin and enjoy a week on a blue-ribbon stream. When the trip is over, drive back to Missoula, give the cooler to the kid washing cars at the rental agency, and head home. Ask me how I know!
I can think of several work cabins in Montana which would be a perfect spot for two couples to access in a single, truck-camper-equipped vehicle, with the camper serving as the sleeping quarters for one and the cabin for another. Come to think of it, I think I'm going to book the work cabin at Twin Lakes, MT next summer!
Foy